I didn't play much of this last night (about 1 1/2 hours), but I'm enjoying it so far. MUCH better than the demo. I almost cancelled my pre-order after the demo, but I'm glad I decided to bite the bullet and buy it anyway.
Only problem I'm having with it is that it's too formulaic. It follows a pattern of combat > platforming > combat > platforming etc... I wish the 2 were combined and enemies served as platforming hazards. However, like I said, I haven't played much of it, so this might change.