I think it's a great game!
The driving is fine. If you don't want to drive 40 MPH, just be good at getting rid of cops. The speed limiter keeps you at 40, so you won't get pulled over for speeding.
The storyline is pretty good. The missions are a bit linear, but still are fun (even that dreaded "Win the Race" mission, which the people complaining about speed probably never reached).
If you liked GTA3, and don't mind the supposed "slow" speed, I would suggest you find a demo version and try it out.
What?