This game IS NOT GTA ... which is no bad thing ...
If you buy this game expecting it to be some kind of GTA clone then you'll be disappointed. If however you're after a good solid driving/shooting game then you won't be disappointed. The ability to target/shoot whilist coupled with the new "heat" feature combine well to make the missions always enjoyable and fast-paced.
I actually thought the storyline was half decent as well. I can't understand how the official Gamespot review knocked it so much. There's some cracking music in the game as well.
Anyway ... to summarise if you're a fan of the series then you'll love this. Oh, it's also ten times better than the lifeless Driver 3.