Easily the single most important thing in any comedy is its strike rate when it comes to the jokes. "I Love You, Man" isn't very good from a visual technical perspective (in fact some of the direction is downright heavy-handed and annoying), but the screenplay and cast keep this comedy consistently funny. There are no terrible scenes, almost every joke is at least mildly amusing (at least until the slightly shaky final act of the film), and there's as much smart humor as there is dumb gross-out stuff (not 'intellectual', 'smart'), and Rudd, Segel and in a smaller role Jon Favreau really nail every line. The comic timing makes this movie.
Above all else "I Love You, Man" is a triumph of comedic acting. The screenplay, by director John Hamburg and Larry Levin (perhaps most notable for writing Seinfeld classics "The Limo" and "The Boyfriend"), is often very funny, but on more than one occasion falls completely flat, and also reveals a dependency on catchphrases and repeated jokes which could have killed the movie. If I were reading the screenplay and 'slap da bass' was said for the hundredth time I would just sigh and throw it in the trash. With Paul Rudd's impeccable comic timing and genuinely convincing take on his character (which, like the rest of the characters here, is really not brought to life by the writing all that well), it had me in stitches.
I don't want to take too much credit away from the screenwriters because this is a (very) funny and enjoyable comedy, but I do have to mention that where "I Love You, Man" falls short of the standard for Apatow productions (and although it's hard to believe this is not one) is in the characterizations. It's far from being as raunchy as those, and is not really as frequently over-the-top, so you'd think there would be more space in the writing for good quality characterization, but these characters are all really thin, and with a lesser cast the movie would not have been nearly as much fun. Now, to the screenplay's credit there are a lot of very effective comedy set-pieces, and the movie's consistently funny. I do suspect it's all a cunning plot to bring back Lou Ferrigno jokes, but the cast pull even THAT off (that includes Ferrigno himself).
The entire movie falls apart just a bit when we get to the inevitable wedding scene, but it's not enough to really undo the movie (which almost veers into "*insert crappy lowbrow maudlin sentimentality-laden wedding comedy here*" territory before quickly recovering), and while "I Love You, Man" only provides a few truly uproarious laughs it is a consistently amusing movie which kept me and the audience I was with giggling and laughing throughout, and Hamburg as director gets the comic timing absolutely right, much like Segel and Rudd do. This is probably the best movie in which Rudd has played a lead role, and is definitely better than last year's "Role Models". The difference in the quality and smarts of both movies is evident in that "Role Models" has a lot of KISS jokes and "I Love You, Man" has a lot of Rush jokes (and an appearance from Rush). It's just a smart and funny movie, and while not a classic for several reasons I've already talked about, it is always funny and isn't that really why we go to comedies, to laugh?
