Will Farrell's latest is almost the classic "love it or hate it" comedy. It's a fully constructed satire rather than the string of pratfalls and fart jokes which characterize, say, Old School. If the premise strikes you as funny, so will the film. If not, you'll think it's just dumb. Personally, I loved it, but I've been on the other side of the coin often enough to recognize that you could go either way.
What is objecticely true is that Ali G steals large portions of the movie as the French NASCAR driver (running the green "Perrier" car, no less). Mr. Baron Cohen may be the Peter Sellers of our time.
The experience is probably audience dependant to a degree - for whatever reason, a film mocking NASCAR Man didn't seem to play well in Anchorage. Funny, that. But if you can see it in some sort of movie pub, it would be absolutely perfect.