Admittedly, it's NOT the BEST movie that was ever made, but it's not the worst either... it's certainly a lot better than most comedy movies these days (like pretty much all those Jason Segel-esque manure piles).
I think another thing about it too is that post-Austin Powers, does anybody even really like Mike Myers? Again, The Love Guru TANKED, BOMBED, FAILED, and was labeled the worst movie of all time (but again still, IMHO, it was good for a laugh), but Mike Myers seems to fall into the same category as Will Ferrell: he's pretty much only good at playing sketch characters, and as such, he's just not going to work out well in a movie. Austin Powers was successful, but the characters from the movies were so one-dimensional, and even when they did try to add some "conflict", it was corny and cheesy.