This re-imagining of the druid, or sentinel as it's called, somewhat hearkens back to the 3rd Edition druid in that it can...well, heal, I guess. Skimming the Heroic tier class features there's no mention of wildshape, which combined with it's ability summon an animal spirit makes this class more like a hybrid of the druid and shaman. Sentinels get to pick from either bears or wolves, each granting a set of passive bonuses and the spirit you get to summon (obviously); bear sentinels deal a shitload of damage with clubs and staffs, and get a +2 to Athletics to boot. Wolf sentinels, on the other hand, can use scimitars, spears, daggers, sickles, get a +1 to hit with them, and gain a +2 to Heal.
As spirits, the Animal Companion doesn't impose some ridiculous XP tax when killed, or otherwise penalize you in the long term. Rather, you can use a minor action or wait until you stop for a breather. Both cost a healing surge, but if you wait til combat is over it reappears with all of its hit points instead of just your bloodied value. The spirits come with their own stat blocks, making them more like ranger animal compnaions than shaman spirit companions, and have auras that either cause enemies to grant combat advantage, or grant a defense bonus to allies. The last two features class, er, features, are Primal Guardian and Combined Attack. Primal Guardian lets you use your Constitution instead of Dexterity or Intelligence while in light-or-no armor. Combined attack is their encounter attack that lets both you and your companion attack with the same action.
It's not nearly enough like a druid from an older edition, but that's okay because I didn't like druids from older editions. This looks like a melee-oriented shaman, and that's also okay because I really like shamans. My only gripe is that like all Essentials classes its not flexible enough to carry my attention for long, and I prefer bear shamans for my bear-summoning primal leader goodness.