I had some fun for a bit. Played a Witch Doctor up to level 7. It's more about quests and such than D2, which is a nice innovation. The skill trees have been changed for the better. You have slots where you gradually unlock skills. These skills can then be modified with runes that you unlock as you level, to tweak them to your preference. I think it'll be a lot more flexible old skill point model, since you're a lot less likely to completely ignore whole branches of the trees.