I really liked Vice City and am getting near the end of San Andreas. I'll definitely buy GTA4 as these are brilliant, polished, funny, entertaining and crazy games.
I could comment on some niggling yet minor issues with the controls, but all in all, they've allowed me to configure the keys and mouse as I see fit.
I bought San Andreas on Steam, but to play mods ( a couple of graphics enhancements), I had to downgrade the exe to an older version. Now I don't need to run Steam or be online to play the game.
As long as I don't get this new bizarre DRM EA's been using lately, I'll buy it. Otherwise I'll wait a year for it to get patched out and drop in price, I'm in no rush.