Just watched Guardians of the Galaxy, and it is every bit as good as people are saying it is, if not better. Definitely one of the best Marvel movies thus far - there's really not a single scene that feels out of place or that goes on too long. They explain just enough that they need to for people to understand (lets not pretend like this is a big franchise) and not waste any time doing so. And yes, it is very Star Wars-ish. I didn't expect it to be as funny as it was either - really everyone on the team (aside from Groot...mostly) has several good lines that will make most viewers laugh. From the commercials (so many commercials) you'd think they give away the whole movie, but they really don't. Yes, they basically do show the ending in the previews (like they did in The Amazing Spider-Man), but not what is actually happening in that scene (you just know that the line is coming up, though with a couple more words to make it even better). If you're on the fence, get the hell off of it and go see the movie.
And I'm glad I didn't read the spoilers for the post-credits scene, even though it is not hyping another Marvel movie (or is it?). It's not. Howard the Duck - no one saw that coming!