i'm really disappointed in the setting of liberty city. it's going to be way more like nyc than gta III, and i'm worried the world is going to be really crowded and that there seems to be a way of getting busted around every corner. in grand theft auto san andreas, you had a really vast world that was filled with variety. you could go in the middle of nowhere straight to the las venturas strip. that game really set the bar for how "amazing' gta IV would be. and so far from the trailer (which really doesn't give me that much information), the game looks really unimpressive. the graphics are good though.
what appears to be the protagonist in this game sounds and looks really cool. he sounds really evil which could be a HUGE part in gameplay, story, missions, and weapons. the accent points out that he could be german or russian or some kind of east european countrian (sorry about the grammer or anything). i think that this could be the best character that the series has ever seen.

the graphics are really great. rockstar has a new technology called RAGE graphics technology. like most games, the parts where you are not really playing, where it is just looking around at buildings and water and skies, look better than the detailed character models. i was really hoping that the whole game would look like a cutscene, that it would be the high def experience for the ps3 and 360 (i have both systems and im probobly getting both versions). but it really doesn't. i mean thats not really a bad thing and i can live through it, but i'm just a little disapointed.
overall, the setting is terrible, the protagonist is awesome, and the graphics are amazing.
*note* all criticism was from the debut trailer, im sure i'm wrong about all of this.