Motorstorm is a fantastic offroad racer. The graphics, sound, and physics are incredible!
I am enjoying both the single player and online play. If you haven't already read, the single player game is a series of "tickets," each of which allow you to compete in one to four races. You unlock more tickets, and also more vehicles, by accumulating points by winning races. The single player experience is a bit shallow, which in my opinion is the only thing that keeps Motorstorm from being a perfect 10. Online play is great. It's as simple as connecting to a server and then joining a race. The race you join may already be in progress, so you may have to wait a few minutes for it to finish. The waiting doesn't bother me too much, but it may boher you if you are impatient or only have a few minutes to play and want to get a quick race in.
The developers have stated that a time trial mode and another track will be coming very soon, as well as more downloadable content in te future. Knowing this, I wouldn't let the lack of modes and relatively small number of tracks keep you from enjoying one of the best games available on the PS3!