Guardian v2 was freaking awesome. I also love all the character growth they've undergone - not just in this movie, but since the end of the first one. Peter was trying to be a more responsible leader (he even chastises Rocket for worrying more about the music player than the incoming monster), Gamora has chilled out a bit and is willing to dance with Peter, Rocket has taken a liking to Peter's music and acts out like a freshly adopted abused-teenager who can't believe his new parents actually love him and is trying to push them away, and Drax seems to gained a basic understanding of metaphors and humor (particularly practical jokes). Groot has actually gone backwards though, but that's understandable since he's basically a baby. Even the villains (especially Yondu and Nova) get some incredible character development, which is rare for a Marvel movie where the villains are usually totally one-note and boring.
The movie is quite a bit darker in tone overall than the first movie, but somehow the humor is even better. There's tons of brilliant call-back jokes to things that happened earlier in the movie and it has the best Stan Lee cameo yet. I just love everything about this movie.
Make sure you stick around after the credits, there's a whopping 5 extra scenes to watch.
