Caught Shallow Hal on FX last night. Saw the end first, then the first two-thirds on the next airing an hour later. It's actually not that bad a movie. It is a flawed concept; you see the ads and think it'll be tasteless and hypocritical. When you actually watch the movie, though, the Farrellys manage to prove their hearts are in the right place, and even Gwyneth Paltrow turns in a convincingly good performance as an appealing girl with a (justifiably) poor self-image. The implications of the movie's high-concept device don't stand up to more intense scrutiny, but you do end up feeling genuine sympathy for Gwyneth as the fake fat girl.
Ultimately, the problem with the movie is just that it isn't all that funny. The story is consumed with its "don't be shallow" message to the exclusion of any real comic set pieces or major story events. All you get are the occasional broken chairs or similar sight gags involving skinny Gwyneth having a disproportionate impact on her surroundings. Even these are not as cruel as they sound, since the source of humor ultimately lies more in Jack Black's confusion than her fatness. But they're not enough to sustain what's supposed to be a broad comedy.