Had fun playing some Forza Motorsport 3 last night. Two-player is a great race mode; you have just enough friendly competition. I have to say the most fun was probably banging million-dollar Bugatti Veyrons off of the barriers in New York City. Also, the twin remade muscle cars, Camaro and Challenger, was fun as well in Sebring.
I was impressed with the number of cars available in Forza. Although Gran Turismo has strictly more cars, Forza has more manufacturers, most notably the ones missing from GT like Bugatti and Lamborghini. And while the game doesn't look quite as good as GT, it is still a lot of fun, and definitely has a more forgiving driving model if you're looking for something not quite as serious as Gran Turismo.