This is infinitely more fun on single-player than GTA. The missions are fun and more varied, the customisation options are vast (cars, clothes, appearance, cribs etc), and the weapons are great fun to use. Different vehicles such as cars, bikes, helicopters, planes, buses, trucks and boats are available, although only the driving vehicles can be customised.
Appearance options are superb, with socks, shoes, trousers, belts, undershirts, overshirts, coats, gloves, necklaces, wrist options, hats and eyewear. Astronaut anyone?!
The real magic of this game does not lie in the multiplayer, in fact it is quite a weak multiplayer when compared to GTA4. The magic of this game is that anything you do in the single-player can also be done in co-op mode. For example, if you have to steal cars on a list, you can drive to one end of the city to find the vehicle while your friend drives to the opposite end of the city to find a different vehicle! All of the missions can be completed alone or in co-op.
You can also buy music tracks and customer playlists. You can use the mobile phone to call in ambulances or even have one of your customised vehicles delivered to you by one of your gang members.
There really are too many things to talk about, the vast array of options is incredible. The downsides are that the graphics are not as good as GTA (although they are still good, just a bit more cartoony) and the multiplayer does not entertain for long. Without a doubt, worth buying if you like the older GTA games like San Andreas.