How do you know what to do?
You have to nip off to a phone box where you receive instructions from one of the criminal gangs. There are arrows pointing out the different districts of the cities, so you're never left in the dark, despite the fact that you can pretty much do what you like, when you like. 'Non-linear', the term is.

What else?
One of the major means to further your criminal cause and win respect on the street is to cunningly pit the gangs against themselves, thereby ensuring a turf war ensues. There are loads of gangs who inhabit different manors in the city, most of them based on those that actually exist in the United States.

Sounds cool...
Stealing police cars, kidnapping people and running illicit drug deals is not cool, young man.

Sorry.
Still, with more than 30 car marques on the streets it seems churlish not to try them all out. And heck, you only have to boot out the driver when the car's stationary and then jump in.

Will I want to buy this game?
Grand Theft Auto is pretty much a cult game and the die-hard fans will snap the thing up. However, newcomers to videogames may be turned off, simply because of the way you view the action. That's their problem, though. DMA (together with Rockstar Games) have licensed a raft of tunes and it should have one of the best game soundtracks of the year.