One thing that struck me about Divinity II is that it was fairly conspicuous that it used the same Gamebyro engine as Oblivion for rendering the world: they have a very similar "feel" in a lot of ways (and some of the modding techniques can be similarly applied to both, conveniently).
I also thought that the voice acting was very much better in D2 and has much more in common with D:OS. I think that it carried the humour a lot better than it did in DD.
