I didn't mind the first one, it was alright. The second one was pretty much the exact same movie set in Thailand. It has some good bits but it's not something I'll come back to, it gets less funny after every viewing.
I'll watch the third one, but I'm not expecting them to reinvent the wheel with it.
Agree that Ken Jeong is annoying as hell: watching an effeminate Asian stereotype speak in ebonics seems to be the height of hilarity for this series (And no, I don't find "Tootaloo, motherfucker" funny AT ALL).
Jeong is pretty much annoying in everything except Community. A little of him goes a long way, and he's reaching overkill at this point.
I may be in the minority, but I CAN'T STAND the character of Stu. An entitled, annoying moron who constantly yells and screams, and I hate how he's made to be the focus of both films, with his whole "I have a demon in me" bullshit.
It looks like the third will stick with the same thing, sadly.