First I just want to say that Dead Space is probably my favorite game of this console generation, so my expectations for the sequel are pretty unrealistic. After playing the demo though, I can honestly say my expectations have been met or exceeded in just about every way.
Just a quick warning, if you intend to play the first game don't watch the cutscene at the start of the demo. It spoils some major plot points of the original Dead Space. Though DS 1 costs like 10 bucks now so you have literally no excuse not to have played it by now.
Anyway, the demo confines you to normal difficulty which kind of sucks because the first game was meant to be played on Hard mode. Still it gives you a good taste of the gameplay, which feels very similar to the first game. If it ain't broken... There are some subtle improvements though. Aiming uses a fixed reticule instead of a laser that projects onto your targets. This makes hitting things like those stupid tentacle monsters way easier. You can switch back to the old style at any time. The guns all have great reload animations. You can fly around in zero G which is cool I guess, but I think I enjoyed walking on walls/ceilings more.
One thing I am still not sold on is the decision to make Isaac talk. I understand wanting to make him more of a hero character, but I dunno. I kind of preferred it when he kept his yap shut. At least then I could pretend he was saying cool things instead of being a whiney bitch. My Isaac would say things like "Don't go to pieces." or "You have been disarmed." I'll give it time though, maybe this Isaac will grow on me.