They're STILL using the same GBA sounds and backdrops, even though this was a brand new game made for the DS? 
Supposedly, the backdrops are higher res and they've remixed the music. The touch screen also plays a much bigger role in getting clues this time around (think PW1: Case 5).
I liked what I've seen from the demo so far. The new characters seem interesting. Apollo looks like he's going to be a good replacement and a funny attorney, and I can't wait to see how Phoenix trains him.
So far? You didn't play the whole thing?? It ends pretty quickly.
I didn't get much out of the demo other than really liking the music...it sounds a bit like Mega Man ZX's BGM tracks, and definitely better quality than the previous games. The first Phoenix Wright still has my favorite BGMs, and this one might end up topping it in that area.
Apollo comes off like a wussy lawyer even in the demo; I can see what the Japanese gamer complaints about the character being overshadowed by minor characters already. Even the defendant had a larger presence than he does. Still buying this as soon as it comes out though.