Underground 2's big claim to fame, so to speak, is free roam. GTA style. I've actually got the PS2 demo courtesy of EA. Now, I will admit it looks a bit cartoonish, but for some reason I find it quite fun. I did play the Juiced demo a while back and it was actually quite realistic looking.
Anyways if anyone is at all interested in Underground 2, I work at a NFS site as well as run a website that makes movies for various racing games(we have rally and racing sim game movies as well).
You can find an extensive demo review I did
here, and if your interested in the movies then go
here.