ok ok ok
nearly everything is improved from Vice City - some things significantly, some more subtley. one thing I don't think they improved on is the radio. some of the stations play some pretty amazing music but the djs (with the exception of the talk radio station) are TERRIBLE!I admit I've only been listening to a few stations but they're just not funny at all. the ads of course are pretty amazing. ANYWAY.
Love the working out thing, and I like that they did away with hidden packages in favor of a variety of collectibles (I've been covering up soooo many grafitti tags). The targeting system is also much more improved - if you get close enough to your target it automatically switched to a head shot. The driving is even better, I think the phsyics of skidding and collisions is much improved and the blurring effect when you're travelling at high speed is much more pronounced. Also the other drivers are more aggressive, if you hit someone they'll often get out of their car with some kind of blunt object and try and fuck you up. Having gang members join your posse is great, and being able to talk back to people that talk to you is awesome.
that's pretty much all I've got as I'm only 4% through the game so far. OH the variety of weapons seems much more vast.