Heroes of the Feywild is a player-centric supplement with a bunch of options and flavor material for players that want to make fey and/or primal characters. It is very focused, and I highly recommend it for any player or DM with a preference that cleaves to its mission statement. My main nitpick is some of the art; there are pieces that aim to feature iconics and tell a kind of story, and those I like.
What I did not like were the Wayne England pieces (just go to the section of pixies and you will see what I am talking about). I really think they should have tapped Tony DiTerlizzi for this project. Despite that it is a superb player resource.
Chapter 1: Into the Bright
The first fifteen pages depict the Feywild from the perspectives of both an outsider and native, as well as taking a close look at major locations there. This is great food for thought for helping players set their expectations, as well as figure out how much they know, and how much do they think they know. The rest is great for players making fey creatures, as well as DMs that want some great adventure sites (as well as a roster of the fey courts). One of the themes set in this book are Bard's Tale sidebars, which tell short stories that might give you ideas or at least give players an idea of what stories they have heard before.
Chapter 2: Races of the Fey
What with the previews we already knew a good deal about the pixie and satyr, and the hamadryad by name at least.
Hamadryads are nymphs that have decided to become dryads, and are stuck in a transitional phase. They get a bonus to Wisdom and either Intelligence or Charisma, gain a bonus to Diplomacy and Nature, are female only, fey origin, can ignore difficult terrain that is based around trees and undergrowth, can last a lot longer--and gain a bonus--when dealing with starvation, gain a bonus on saves against daze, dominate, and stun, and can use hamadryad aspects.
Hamadryad aspects is kind of like the original version of a drow's lolthtouched racial, in that each time you use it you can pick from two different effects, causing each enemy that can see you to grant combat advantage or gaining damage resistance for a turn (making it better than a goliath's stones endurance). They can also pick from racial utilities that allow them to do stuff like gain temp hps and a bonus to AC and Fortitude (with the side effect of fire vulnerability), or gain phasing and insubstantial for a turn along with a short-shift.
Seeing as the pixie's stat block was already previewed, discussed, and condemned for ruining games, so I'll just note that their racial utilities let them--among other things--use a minor action to automatically affect a creature with a random effect, turn invisible for a turn, and grant all adjacent allies flight for a turn (and that one is only 6th-level).
As with pixies, satyrs also got their stats revealed. Their utilities let them jump really far, cause a creature to regain more hit points or take more damage than normal, and turn into a "satyr of the night", which gives them concealment (or invisibility if they'd normally be concealed) and heavy necrotic resistance.
Chapter 3: Classes
There are four new subclasses, complete with backwards compatible powers for their parent classes.
Berserkers are martial and primal defender and strikers. One of their defining features is that they gain a passive benefit depending on which terrain they favor: arid desert gives you fire resistance and a huge bonus to AC and Reflex in cloth armor, frozen land gives you cold resistance and a bonus to Fort and Will, and temperate land gives you a damage bonus when using a shield and a boost to Speed when charging.
Like knights they have a defender aura, but when they get to smack someone for violating it they deal scaling bonus damage. They cap out at hide armor, but gain a bonus to AC while their defender aura is up (putting them on par with fighters so long as they have are at least pulling 2 more points from somewhere). The problem is that when they use a primal attack--either an encounter or daily attack--they enter a berserker rage, which lasts for the rest of the encounter and shuts down the aura, but you deal bonus damage and some of your attacks gain extra benefits.
This creates an interesting class dynamic in which you start out as a defender (though your triggered aura attacks gain a damage bonus), but can switch over to striker as the situation warrants. Not all of the encounter and daily powers are primal, so you can opt to just take the martial ones if you want to stick with a defender. All of the attacks and utilities have levels, so even if you are going with the core barbarian you will have a bunch of stuff to choose from (though the at-wills are kind of lame in comparison unless you let barbarians always benefit from the Berserker's Fury bonus).
Skalds are an arcane and martial bard variant. Their key schtick is skald's aura, which allows any ally within it to use a minor action to heal themselves or an adjacent ally, which a starting cap of twice per encounter. Skalds use their at-wills and dailies to modify the other affects of the aura, granting allies that hit enemies temp hps, or a bonus to their damage, attack roll, or defenses. Like most subclasses, they are centered around basic melee attacks. Not only can they use their Charisma modifier when handling them, but their encounter spells trigger on successful hits.
There is also a pretty extensive section of class features at the start of the section that you can swap out with existing bard features, giving you benefits of attracting attendants when in town, gain an audience with a political figure, or get free stuff like carts or carriages.
Sentinels were kind of a step back to 3rd Edition druids in that they could heal allies and got an animal companion. Protectors kind of remind me of 2nd Edition druids in that they belong to druidic circles (though you still don't have to fight anyone to level up). You start with nature's growth, which creates an encounter-long zone of difficult terrain with a scaling area of effect. Depending on your circle the power also lets your allies heal more when they burn a surge next to or inside it, or simply ignore it as it does not come equipped with friendly fire.
The real meat of this class is its key feature: summon nature's ally. You do not gain daily powers as you level up, instead gaining the ability to summon more--and better--monsters over time. For example, at 1st-level you can summon a giant cobra or desert hawk, but once you hit level 15? Time to call in the bulettes and/or giant scorpions. Eventually you can conjure blue dragons and rocs, but baby steps, ya know? Otherwise they still get a nice collection of evocations to choose from, including dailies for other druids.
We got a taste of witches previously, and since this section is going on long enough will just gloss over it. It is a wizard subclass that gets a familiar right out of the gate, which lets you swap out your daily attack and utility spells. Basically it is a spellbook with no limits. You also pick a coven, dark or new moon (which means generally evil or good respectively). Finally, you can cast an augury once per day in order to gain a vague notion of something similar to cleric spells from older editions.
As with the mage subclass and all the new schools they got later on, there are a shitload of new spells that you can use with any old wizard (though the forums will rapidly argue that there is no "classic support"), including lots of polymorph effects for the budding transmuter out there.
Chapter 4: Character Options
This chapter has new themes, paragon paths, epic destinies, feats, and loot both mundane and magical.
Skipping over the fey beast tamer we get the sidhe lord. These guys are fey only, and start you out with a daily summon that basically spends most of its time taking hits for you until it runs out of hit points. The level 5 feature has some good social applications, allowing you and your allies to receive free room and board in any place that recognizes your house. At level 10 when your summon teleports you can also teleport with it as long as you are next to it.
The utilities allow you to have an ally burn an action point to take a standard action, gaining the action point if they do so, move you and your summon with a speed bonus with the same move action (and gaining temp hps to boot), and--my personal favorite--create a pact with an ally, allowing them to yank your encounter and daily powers to recharge their own, as well as nabbing their healing surges for your own personal use.
Tuathan are basically fey-touched humans or half-elves that can gain shapechanging abilities, but start out gaining a bonus on death saves or rolling Athletics checks twice. At 5th-level you ignore cover and concealment after using second wind, and at level 10 you can change into a bird if you picked up the level 2 utility that lets you change your shape, or treat modified 20 death saves as a nat 20 (with the added perk of standing up as a free action).
These guys get to choose between two utilities. At level 2 you can pick from rolling a 20 and saving the result for later or changing into a tiny fey or natural beast, at level 6 you can force a target to always speak the truth or mark a target (gaining temp hps each time you hit the target), and at level 10 you can force an attack to be redirected to another target or generate an aura that causes all weapons to gain Brutal and slow enemies, or burn it during an extended rest to reduce the time to 4 hours.
Last but not least is the unseelie agent. Any race can go with these guys, gaining the ability to conjure a magical, shadow-wrought weapon as an encounter spell. It can be ranged or melee, and the enhancement bonus scales as you level. Not bad, which is nice because the level 5 feature lets you speak the Unseelie Fey language, making it about as useful as Druidic or Theives Cant in past editions. Level 10 wraps things up by letting you roll Intimidate twice.
Moving on to paragon paths, there is one intended for each of the subclasses in the book. My favorite is the legendary witch, predictably an extension of the witch subclass that gives you varying spells based on your coven (except for level 16, where they all gain a sustain fly encounter). Mostly I like it for the level 20 daily, which lets you turn into a nightmare or unicorn depending on your taste.
There are only three epic destinies. One has you become the champion of Queen of Summer, a master of the Wild Hunt (complete with a daily 26 that lets you summon hounds), and a witch queen that is good for even vanilla wizards.
There are also a lot of pretty cool feats, including race support--if a bit anemic--for everything fey. For example, High Elf Kin lets elves use teleport after using elven accuracy, Fey Thievery lets eladrin use fey step to make a Thievery check at a distance, and Teeny Target grants you cover while in an ally's space (which asmRandy pointed out would make pixie defenders even more annoying). There is some old stuff like Totem Expertise and Arcane Familiar, though two-handed weapons get some love with Two-Handed Weapon Expertise (bonus damage when charging).
Feywild gear is a lengthy list of mundane stuff, like cold-iron shackles (fey cannot teleport), faerie puppet (can move on its own, making it nifty for a distraction), and a rain stick (break it to make it rain in a huge radius). A lot of this stuff seems better fleshed out, I guess? Like stuff you saw in Mordenkainen's Magnificent Emporium, where some of it might require DM interpretation to arbitrate.
There are not a lot of magic items, and one of them is your run of the mill magic totem. There are some interesting bits though, such as the hill tamer crook, which reduces a hill to level terrain. Definitely room for player creativity, especially given that there is no maximum size. The hag's doorknob was already previewed, but I have to call attention to it again: it is a doorknob that you can attach to a section of wall, and open it as if it were a door. Since it is level 12, this is not something that just anyone will have, and I could see a short adventure where players have to steal one of these things.
Fey magic gifts are divine boons and grandmaster training by another name, though I do like a system by which you can rewards players with intangible "items". The lowliest gift allows you to give a bunch of critters with the Mount keyword a speed bonus outside of combat, with the best allowing you to sense birds within a half mile of you, and see through their eyes if you want. Oh hell yes.
Chapter 5: Build Your Story
This is a really cool chapter that is basically a massive random background generator, and why oh why has WotC not made one of these for the implied setting? I remember one of these things in 3rd Edition's Hero Builders Guidebook, which even if you did not use it word for word it could still throw you some interesting flavor curveballs, and this one is no different. Without going through all the potentials you determine who raised you (eladrin nobility, feydark refugees, etc), and depending on the result get to choose from several areas where you grew up, ranging from an eladrin city to the Isle of Dread to one of the fomorian cities.