Weather & Warriors, with a few paragraphs at the end about rules complexity and future packet updates.
If and how I use the weather can vary quite a bit from adventure to adventure. Usually it functions as window dressing, but sometimes I throw in rain or snow to limit visibility (which can work in the characters' favor), or make it difficult to climb (or even move, in the case of ice).
I tend to emphasize it more in Dark Sun, what with its focus on survival due to the inhospital everything and lack of food and water. I am a fan of tables, and have used random weather before, I just prefer that its mechanical impact does not require too much bookkeeping.
Of greater interest is the plan to change fighter maneuvers so that they are an additive to damage, instead of forcing you to choose between dealing damage--generally considered the more optimal option, as it tends to be the fastest track towards the dead condition--or doing something interesting. The small paragraph on how this works reminds me of the warblade from 3rd Edition's Book of Nine Swords, where you had a list of maneuvers that you could use once, but you could use a standard action to make a normal, run-of-the-mill melee attack to refresh them all.
The summary here is that you get a pool of dice that represents skill and energy, which you to perform maneuvers, and can use an action to take a break and regain some of it. I am curious that if scaling damage is going to become its own thing, why they have to use dice at all? I do like the mention of spending an action just to regain some of it, as opposed to all, as it forces the player to choose how much energy she wants to use at a given time. I am curious if the fighter will still get to make an attack (like the warblade), if you get a defense bonus, or what.
I wonder if there will be any class features or feats that let you regain expertise, such as by defeating a monster, parrying an attack, landing a critical hit, etc.
As for the bit on spending feats to open up maneuvers, I am not sure what to think: most 3rd Edition feats that I remember were pretty meh, often giving you a small numerical boost to something (Weapon/Spell Focus), or giving you access to a highly situational ability (Cometary Collision), though some, like the Reserve feats from Complete Mage, were pretty cool.
To be fair 4th Edition had its share of boring, arguably mandatory math-boosters (such as anything Expertise), but there were also many more that shook up both your race and class features (such as Agile Superiority and Defensive Bluff for fighters and halflings respectively), as well as let you combine certain races and classes in thematic ways (such as Distracting Challenge for gnome paladins).
At the least 5th Edition has more hits than misses for me (I wish Arcane Dabbler let you choose your cantrips). Granted there are not many to choose from, and it is still in its playtesting phase, so hopefully we will avoid an insurgence of +x to y feats, and whatever maneuvers you end up being able to purchase are worth the cost (or trap choices).
The last part mentions rules, rules complexity, DM styles, stuff that we have already heard about plenty of times by now. As I have said before I like the idea of being able to set the bar on rules complexity, but am still waiting for an actual example to see how they are implementing it. Hopefully when we get the exploration rules that they come with a "dial' for people to mess with.