Wedding Crashers is not the most hilarious thing ever, but it's enjoyable, if overlong. Owen Wilson and Vince Vaughn have excellent chemistry and play off each other well, resulting in a comic duo stronger than either one opposite Ben Stiller. Unlike Stiller, who often feels like he's hogging any scene he's in, Vaughn and Wilson share scenes with easygoing teamwork. In the end Vaughn comes out as the funnier of the pair, but he's written that way.
The third act/second half of the movie is where it starts to feel long. There's a weird anomaly at work here where the movie is both utterly predictable and unpredictable at the same time. That is, having crossed the romantic comedy checkpoint where the Lie is Exposed and the Girl is Pissed Off, we know we're headed toward a climax where a Wedding is Interrupted, there's a Heartfelt Speech, and a Happy Ending. But the route we take to get there is bizarre and unexpected, and not entirely in a good way.
It's like instead of taking the freeway to its destination, the movie gets off at a different exit and winds through some wilderness backroads on a long and confusing path. Yes, it's interesting and unpredictable, but you can't see the road signs and you don't know how many miles are left to go and you worry about whether the driver will ever get where you're going.
Once you're in the home stretch you start to have a feeling for being close to the end, and when a movie violates that feeling you get restless.
The movie is funny, though seldom really funny, and the guys are likable if you like those guys. Some threads, like the lustful mother, are set up effortfully and then suddenly abandoned. The boyfriend from whom the girl must be stolen is a ridiculously over-the-top asshole.
Also, I saw it like two weeks ago and didn't bother to write about it until now, so if that says anything, take that into account too. Perhaps not seeing a movie until everyone else has already anointed it hilarious hurts things too.
Speaking of overrated things with "crash" in the title, Crash is surprisingly good but also heavy-handed, phony, and emotionally manipulative, which people overlook because seeing a movie that Addresses Racism makes them feel so good about themselves that they want to love it anyway. On the upside, all the characters surprise you by having a good side and a bad side and the movie mostly avoids making pat judgements about them.