Yeah, I just finished the demo myself and I really like the game. I have some nitpicks, like how I really don't like this game's voice actor for Commissioner Gordon (they needed to get the guy from Batman: TAS); I wish the Batarangs could interact with more than apparently just enemies and TV screens; and the demo really should have let us fight Killer Croc, but if this snippet of gameplay is indicative of the whole (and I'm still wary of that) this game's going to be awesome. It doesn't seem to be a particularly hard game, but I love how it boils down the essence of what Batman does and then makes it easy to do. I'm a little annoyed that a filter toggle seems to be the extent of the investigative side of Batman, but otherwise they seem to have pretty much nailed the feeling of being Batman. There is just a very simple joy in sneaking around a room, grapping from ledge to ledge by means of a simple button press, isolating a goon, and then jumping down to grab them and yank them back into the shadows for a very Batman-ish stealth finish. By the demo I was doing that non-stop, easily the most fun I've ever had in a Batman game. Hopefully there's a lot more depth to be uncovered, but I'm quite content with what's here.
EDIT: Actually, something I forgot to mention: anyone else bothered by just how close the camera is to Batman in this game? It's like RE4-level closeness and feels really claustrophic when I'm walking around environments. It was bugging me throughout the demo.