Ah, the curse of the comedy sequel. You almost can't win. Fans of the first film want to see their favorite elements revisited, but they get mad if it's TOO similar, because then you're just being lazy. But if you veer too far from the path established by the first movie, the fans are disappointed about that, too. To summarize, then: a comedy sequel needs to do exactly what the first movie did, but differently, but not too differently, and not too much the same.
I didn't laugh as much as The Hangover Part II as I did at The Hangover -- maybe because the simple-yet-brilliant scenario is no longer fresh, and maybe because there's a stretch of, oh, I don't know, 30 minutes where nothing particularly funny happens. The guys who wrote the first movie aren't credited on this one, but they should have been, because I get the feeling the sequel was written the same way "Saturday Night Live" redoes sketches: they copied and pasted the original script to preserve the structure, then just replaced the details.
So instead of Las Vegas, the guys are in Bangkok. Instead of waking up with a missing tooth, Stu has a tattoo. (It can't be someone else. It has to be Stu. Because it happened to Stu the first time, you see.) Instead of a baby, there's a monkey. Instead of having misplaced the groom, they've lost the bride's teenage brother. Instead of criminals and strippers, there are different criminals and different strippers (VERY different strippers).
The groom this time is Stu (Ed Helms) himself. He's marrying a Thai girl named Lauren (Jamie Chung), with the ceremony to be held in her homeland. Phil (Bradley Cooper) and Doug (Justin Bartha) fly out for the occasion (as do their respective wives, but mostly just so they can answer the phone and say, "Really? It happened again?"). Doug's brother-in-law, you will no doubt recall, is Alan, the bizarre and possibly mentally handicapped man played by Zach Galifianakis. He is sad not to have been invited to Thailand for the wedding. And heck, it wouldn't be much of a Hangover sequel without Alan, so the guys relent and invite him after all. Now the only question is: How will they get Ken Jeong's Mr. Chow involved??
Everyone tries very hard not to have a repeat of what happened last time someone was getting married, but one thing leads to another, and next thing you know you're in a seedy Bangkok hotel room and Lauren's brother, Teddy (Mason Lee), is missing. The guys utter a lot of variations of "It happened again!" and "I can't believe this is happening again!" I guess we should award the film a few points for acknowledging how odd it is that the same misfortunes keep befalling the same people. A lot of sequels gloss over that and hope we won't notice.
Some points for nerve should also be awarded to director Todd Phillips, who co-wrote the screenplay with Craig Mazin (Superhero Movie) and frequent collaborator Scot Armstrong (Road Trip, Old School). The degree to which the film duplicates the original story is astonishing -- not just the basic scenario of not being able to remember a wild night, but specific plot points, and in the same order. Basically, if you want to avoid spoilers for The Hangover Part II, don't watch The Hangover.
As with the first movie, the sequel eventually descends into a period of frantic outrageousness in which the mechanics of the plot must be carried out whether they're funny or not, and they often are not. As a character, Phil barely registers (Cooper still gets top billing, though), while Stu continues to be likable, if a bit prone to hysterics. Most of the laughs are thanks to Alan, including several non sequiturs that I would bet came from Galifianakis and not the script. He's a lively, unforgettable character -- but even he can't compete with the version of him we saw two years ago, the one who was new and had not already been rehashed (essentially) in Due Date.
The Hangover, if not exactly revolutionary, was a perfectly good raunch-com that showcased the different skills of its actors. Its sequel is more of the same, only less so. Why pay to see it when you could just re-watch the first one?