Back to the 80s...
Gameplay: The 80s setting is definentely a neat trait of this game. You have beaches, to palm trees, to city area, night clubs, ect. This is just like GTA 3, as where you can just run around and cause trouble if you want. The more trouble you cause, the harder it gets to lose the cops. Sometimes it gets a little too hard to outrun them, which makes it a bit annoying at times (i.e. the spike strips). Another thing you could do is buy property; this was first introduced in this game. You could buy safehouses are properties, which usually came with a few missions or a way to get an asset for it. Free-roaming can definentely keep you occupied in this game.
Missions: The missions in this are a lot more detailed than those in 3. They actually had a story to them, instead of the crime boss just immediately telling you to do something for him or her. The ok, somewhat boring missions seem to clump towards the beginning, as where the good ones at the end. Buying property was something you had to do to activate missions, too. This could be annoying, considering money doesn't just come to you, you had to collect it, which took quite a while (like the expensive Malibu Club). The side missions were mostly just the ones in GTA 3, with one or two new ones added, like the Pizza Boy missions. The missions in this game tend to be fun and really pull you into the game.
Graphics: Many people complain about the graphics in the game. Yes, they are worse than the ones in 3, but does that make them bad? No. They are meant to be the way they are because of the fact that you're in the 80s. If they used 3's graphics again, you wouldn't quite be able to tell you were in the 80s. Some buildings seem to load slow in the game, and the look of certain buildings and cars can seem weird, but overall the graphics aren't really that bad.
Grand Theft Auto: Vice City, is a game that I'd definentely suggest picking up.