I have just completed this game for the second time. For those who haven't bought it and are doubting buying it i will say, don't think this will be like GTA3. Its not.
The city is the same layout but bits are different. I wont spoil it as its worth two days constant playing it.
The only real problem i had was trying to put it into a time line with the others. GTA, GTA London and GTA 2 aren't part of this saga. GTA3 GTA VC GTA SA and Liberty City stories form a saga but there's no logical pattern into which order that go. So far I've decided its GTA SA, GTA VC, LCS and then GTA 3 last.
Anyway, my logic aside, if you love the first GTA's you'll love this. Just remember, its 18 so not for kids.