I talked a bunch of shit about this movie when it was announced, so I'm eating some crow when I say that I enjoyed it. It was like a less serious version of Star Wars, pretty cool. I don't feel like it added a whole lot to their cinematic universe, but personally I prefer it that way. I have to wonder if they'll have a place in the Avengers movie. It would be weird to see Rocket Raccoon fighting alongside Captain America.
This movie actually adds more to the cinematic universe then any of the other films combined. We are introduced to (among other things) the Kree, the Novas and the Celestials. We are also given more details about the infinity gems and Thanos (who is pretty much guaranteed to be the bad guy in Avengers 3).
I suppose "added" was a bad word, what I meant was that it didn't "expand" on a whole lot. They introduced new stuff (like what you mentioned) but the stuff from the other movies was left pretty much alone (unless you count Thanos as a previously introduced element which I don't). There was no Nick Fury, no mention of other heroes, or anything like that. Whereas Iron Man 3 dealt with a lot of The Avengers fallout, and Winter Soldier had a lot to do with SHIELD. It was very much its own thing, which I liked.