Vice City is almost twice as big as Liberty City back in GTA3. With 4.25 million virtual square meters you have a lot of space. Of course it isn't all grass and playground.
The city is packed with a far greater amount of detail and variety than Liberty City could have ever hoped to be. The map contains a mainland, three smaller islands and one big island called "Ocean Beach".
At the end of development of GTA3, the whole team at Rockstar's Scotland branch was sent off to Miami for a vacation. At the same time they collected 10,000 digital photos and countless hours of digital video. This all helped them to recreate the feeling for Miami, including exactly how the babes rollerskate on the shoreside!
The map was structured with gameplay in mind, and it is based quite closely on the real Miami. Rockstar however wanted to avoid the scenario in which gameplay would suffer in favour of realism. The game is meant to be fun, not a Miami simulation!
There are many different districts in the city. There are shady districts with shantys and electricity posts, and also modern skyscrapers and huge shopping malls. Variety is key toward development, and Rockstar say it will be very hard to find repetition in the game.
There are around 60 or so interiors. Within the huge shopping mall of course there are interiors within interiors, and as such it's all much more accessible than in GTA3. All the buildings are unique, and there are many more alleyways, rooftops and jumps for you to explore.