I'm on chapter 5 of DS2 (which does seem to suggest it's a short game, I still feel like I've only just started), and I have to say, so far I'm not enjoying it as much as the first game. May have done myself a disservice by replaying the first game again just before starting DS2, but so far all the nice little touches I liked in DS are gone or diminished in DS2. There's no real feeling of tension or atmosphere either, it all feels a bit dull in comparison. Still a good game, but it just seems like they're throwing things in your face a lot more this time round.
The voice acting so far is fairly poor too, I don't feel convinced by any of the characters really, especially Isaac himself. He sounds like an office worker who swears a lot, not a man suffering dementia as a result of what he's experienced.
I'm not disappointed with the game, just disappointed that Visceral seem to have forgotten to include a lot of the little things that made the first game brilliant.