Go see it.
This was seriously good, much more space opera than superhero movie. I was not a fan of the original comics (in fact, I don't think I ever read them, and was only vaguely aware that "Rocket Raccoon" has been around for a while as an actual Marvel character), and I kind of raised an eyebrow that this was the next big Marvel movie.
But hot damn, it was awesomesauce.
You don't need to know anything about the Marvel Universe to enjoy it. But even though this is a completely stand-alone movie, Marvel fans will appreciate all the references: the Collector, Ronan the Accuser, the Kree, and the Nova Corps, and of course the little easter egg after the end credits (my reaction: "Nooooooooo!") may be somewhat obscure, but they have long been part of Marvel canon.
And obviously they are working up to Thanos being the Big Bad in some future movie. Personally, I am waiting for Galactus to show up. (Yes, I know he kind of did in the Fantastic Four movie, but that sucked and wasn't part of the current franchise.)
The reference to the Nova Corps makes me hope that someday Nova will join the movie Marvel Universe, because I was a fan of ol' bucket-head, the original.