I think the Druid is too good right now.
Druids are just as good at spellcasting as wizards are, and even have some advantages (imagine a wizard with Heal). They even got some of the best wizard spells added to their list, including Charm Person, Thunderwave, Hold Person, Web, Confusion, Dimension Door, Dominate Person, Feeblemind, Dominate Monster and even Wish! They never had any of these spells before, and their spell list wasn't exactly weak in 3.x. They also get spells at the same level clerics and wizards do, so no more level penalties on things like the Heal spell or Wall of Fire. With the exception of Thunderwave and Web, I don't think Druids should have any of the spells I just listed. They're supposed to be good at controlling plants and animals, not people.
And then there's the Oak Druid. At first glance, I thought, gee, these animal forms kinda suck. Then I noticed Shape of the Dire Beast. Good grief. With that feature, Wild Shape basically becomes "I turn into a fighter++" A Dire Behemoth does 15d6 +4 (19-94) damage at level 20. Seriously. And it's AC can be as high as 20. A fighter at level 20, using a two-handed weapon, is doing 5d12 + 5 (10-65) damage. Druids need to have the +[W] damage removed from dire form and just have deadly strike like clerics (up to 3[W] at 19th level). Then, not only can a druid use weapons if he wishes, his dire behemoth from would be doing 9d6 +4 (13-58) damage. That's more like it.