Great single player + deep online multiplayer = a game that keeps you satisfied long into its life.
It features over 300 full licensed cars, albeit some of them are tuned versions of other cars, 12 racing places, most of them real-world places e.g Laguna Seca, most of which can be driven in a variety of different routes and one of the most extensive customisation abilities. Forza 2 gives you a paint option which you can create all kinds of different paint-jobs and, if you're good enough, real-life racing liveries.
I've had the game for over a year now and I am still playing it on a regular basis. It revitalises your racing enthusiasm when you build a car from scratch and nurture it to become a race-winner. The game also feature online tournaments which have a knock-out stage layout in which over 64 competitors battle it out to become the fastest.
Forza 2 is an excellent racing simulation and is well worth the buy.