Even though it's already the third movie, it's still entertaining. There's some random humor, and is still obviously one of the hangover movies, it's just not like the original where you are shocked and laughing from beginning to end. The first one was funny because everything was reckless and ridiculous, yet ended fairly harmless. This one there's actual consequences which just isn't as funny. Good movie, just no where near as good as the original.
If you read the books, it's alright. They add in things that never happen, alter things that don't and the acting is never really how the characters seem like they should be. They never even explain what the half- blood prince means, they say who it is, but not why. But if you don't care about the book or don't read it, it was a good movie strictly because it was a really good book. it was kind of funny and for a two and a half hour movie, it does manage to keep your interest.