Shouldn't come as a surprise that The Hangover Trilogy holds a special place in my heart.
Not going to give some lengthy review on the movie(s), but I will say that the third installment disappointed me slightly. The characters are there, and they're even better than in the previous two movies, but the plot is completely different. Instead of the usual backwards storytelling, this one plays out like any other action comedy. And it's also much darker and more serious than the previous movies (three people actually get killed in this one). Most importantly, though, there's no hangover sequence in it. None. The characters do not lose consciousness, and there's no trying to sort out the events of the night before, although the deadline is still present, and Doug still gets to be the one left out of the Wolfpack.
I enjoyed the movie for what it was, and the final scene with the flashback sequence brought a manly tear to my eye (see below), because it's been a good four years, and I really liked where they took the Alan character (Zach Galifianakis is a great actor). In order to justify the movie's title and part in the trilogy, the director threw in a hangover moment mid-credits, so do watch the credits if you haven't. Worst part about that scene, though, is that I really, really, REALLY want there to be a Part IV now.