Hangover 2 (2011)
Rather than write a full review of The Hangover Part 2, I'll keep this short. It was hilarious.
I've heard complaints that it was the same movie as The Hangover. It's the same type of humor, and the group is looking for someone they lost again. Other than that, I'd say that it's a different movie that it completely worth watching.
The only thing that detracted from when I watched The Hangover Part 2 was that people brought babies and children under 4 years old to see it. I don't care about what you think is and isn't proper parenting, but when you attend a movie intended for adults, keep your kid quiet or get the fuck out. I can't complain at a G rated film, but a night showing of a rated R film should not have crying babies.
Ultimately, if you liked The Hangover, you'll like The Hangover Part 2. Rotten Tomatoes calculated a 35% critic rating, but users gave it 94%. Critics don't know what they're talking about.