Great game with a long story line
The driving in GTA 4 will take some getting used to, at first i thought to myself that "wow i cant drive at all..." but as you progress through you will realize that its actually better than the driving styles in old GTA games.
Hmmm...guns, they are somewhat a little realistic that past installments, also bullets actually spread in this game! Bad thing is most of the fun weapons in old GTA games are gone (FlameThrower,ChainGun,etc).
Missions are in my opinion are recycled from old games like tailing a car but not getting too close and a normal go to this place and kill everyone sort of thing. But dont fret there are some missions in the game that we havent seen in past GTA titles.
Finally the AI, i have seen other peoples reviews and GS/GFAQ's reviews and they say the artificial intelligence is bad, i would disagree. Ai has had great improvement! You'd see cops going for cover and civilians reaching for their gun against you!
All in all GTA 4 is a must have game especially if your a hardcore shooter/adventure/action lover or just willing to see if GTA is a great franchise for you. In my opinion its not worth its $60 price tag (maybe b/c its not every month i can get a game that expenisve:p) but it still has somethings that doesn't make it as comical as the past GTA games were i would personally say $45 is when you should buy it.
Hope this helps you making your decision for buying GTA4!!
(WHICH YOU SHOULD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!)