I really liked this movie, a lot. For all the people who said it would be a "fail because they're so unknown and it's their first movie," you can suck it. In terms of setting up characters for future reference, this was a great way to do it.
Even though they have only around two hours to introduce five main characters, you never feel like they're rushed into your face or forced upon you. (Learn from this, Spider-Man. Learn.)
Everyone goes crazy over Groot and Rocket, but my personal favorite would have to be Drax. He probably had the most quotable lines, especially since nothing can go over his head
The action is great, especially once you get all of the Guardians on screen, you can see each of their different ways of fighting mingle with eachother.
As for the main villain, Ronan the Accuser, as much of a good job they did with him, I wish he would've been a bit more.... Silent but deadly. It's apparent when he fights that he's a hulking fellow, who doesn't need to do much to send you hurtling across a room, but he shouldn't have to do it with so much taunting.
I also have to admit that while I love htis soundtrack, it does feel out of place sometimes, like someone went into Movie Maker and just added in their favorite songs. I like to think that's what they were going for, but who knows.
And I swear, if we get a Howard the Duck movie before we see Black Panther, I'll go insane >:C