In my experience, the Hangover movies are mildly amusing when they aren't despicable. They are founded on a clever premise (retracing the steps of the blackout night before). They relish the joy and profound weirdness that stupidity can produce. They touch on relevant cultural practices and obsessions like eternal adolescence, bro culture, the mispronunciation of words and asshole-spotting.
The Hangover Part III is more despicable than amusing by a wide margin, though. This has a lot to do with Ken Jeong's amplified presence as Leslie Chow. That snake with the voice of a deflating, pinched balloon is all over this movie and perhaps the most inexplicably popular, aggressively insufferable character since Austin Powers' Fat Bastard. He is alternately moronic and cunning, both of which serve the film's Murphy's Law-fueled plot. He makes lame jokes (crawling on the floor to avoid triggering the security system of the house he just broke into, he sticks his nose in the ass of a fellow crawler and explains, "I’m saying hello. We’re dogs, remember?”) and lamer references (he sings "I Believe I Can Fly" as he parasails over Vegas). He is, clearly, a stew of stereotypes — he's described by another character as having "an Asian accent," which is dead on in its nonspecificity. Speaking of nonspecificity, Jeong has defended this character by explaining that the actor's awareness of the stereotypes he's conjuring make this character an example of "meta-humor." Perhaps it is in his head, but then that's just an inside joke – the movie profits off this character in traditional "Asian people are simultaneously stupid and threateningly crafty/unable to speak English/sexless/probably gay/small-penis-having" fashion.
We do inhabit, after all, a gently white supremacist universe when we drop by The Hangover. It is a place where there is a Black Doug and a regular Doug who needs no qualifier because he is white, duh. This a franchise that believes that anyone who isn't a straight white male is inherently funny (the penis of a person that audiences and characters were led to believe was a biological woman was the sight gag of the second film), and that variations of hilarity within straight white males come from where they sit on the dickhead scale. One of The Hangover's admirable qualities is its audacity, its bold going where most of its ilk will not. I'm not suggesting that you not laugh at whatever strikes you funny, even if you have to later lie to yourself using the word "meta." Enjoy these films. It's all jokes. Jokes help us cope, goes the conventional wisdom of routine offenders. Let's just know what we're laughing at.
Much of the humor that isn't based in degradation of immutable traits comes from Zach Galifianakis' Alan character, a savant of idiocy. He gets the best lines and delivers them better than this movie deserves. ("I can’t believe my daddy is dead. I can think of so many people I would have rather died first. Like my mother," is how he eulogizes his father early in the film.) Galifianakis' amazing feat in this franchise and in general is creating chemistry out of awkwardness – chemistry that, oozing from a lesser talent, would repel. He gets some funny scenes with a potential love interest played by Melissa McCarthy, whose fading Manic Panic purple hair is about the most dead-on observation of the film. He also gets to decapitate a giraffe he's transporting on a highway via a low clearance overpass. Get it because it's tall and the low clearance overpass isn't as tall?
Unlike the second film, which was more polemic than movie ("You were stupid enough to laugh at the first one; you're stupid enough to laugh at it all over again," is what it said), The Hangover Part III doesn't share the structure of the first. This is not a retracing of steps. In this one, the typically bachelor-partying group's association with Chow ropes them into tracking him down – their task as obligatory as the actors' in a squel to a billion-dollar franchise. And so, through a series of setbacks and miscalculations, the film glides along on the stupidity of its characters that it wants to punish and reward for having. Who cares anymore at this point? The tagline on the posters for The Hangover Part III is "The End." I'm not sure I believe that, as its final scene suggests otherwise. If it is, that tagline is the movie's best joke. God help us.