Interesting questions on the vide, hopefully this will go way beyond GTAIV, at present I really can't see myself completing the single player but I will enjoy the multiplayer definitely. Would be nice to see some really imaginative and distinctive multiplayer modes, had great fun with Payne Killer and Gang Wars on Max Payne 3 - they could take several leaves out of that game, particularly with the combat, which is looks like they have done already.
Not sure the customisation really appeals, and the special abilities of the character seem slightly gimmicky. Making them different is nice, but you might find yourself missing your favourite when the game makes you play as someone else.
I'm waiting to be impressed, but then I'm pretty hard to please with games like this.