As a whole, I'd have to give it just a B so far. Marvel has done a great job with casting these roles, and making their characters look believable on the big screen, but the movies themselves have just been so-so in my book-- with only the first Iron Man and Avengers really breaking out and coming alive like Raimi's Spider-Man or Singer's X-Men did. The rest all feel a bit too safe and overly-manufactured somehow, and seem to be missing any real spark of originality.
When the Term "Marvel Cinematic Universe" is used, it typically only refers to what Disney has rights to (Not the Fox and Sony Movies). So, XMen, Fantastic 4 and Spiderman, should not be included, Dsiney doesn't have those rights, and so, they are not in the same Continuity/Universe. I've enjoyed all the Avengers Movies I've seen (Haven't see Thor 2 yet) and I'm looking forward to Avengers 2, Thor 2, CA2 and Guardians of the Galaxy. I haven't seen enough about AntMan (And don't know anything about the comic) to be excited for it.
I'm talking about Sam Rockwell's antics being more compelling than fixing a helicarrier engine, and I'm talking the big Stark/Killian/Jarvis-controlled suits/AIM fire-mooks being more fun than Stark vs. Thor vs. Cap brawling and verbally squabbling. Also, Pepper Potts is a far more interesting character than Romanoff.
If you love em fair enough, I just mean to say, IMO none of them will really be remembered as genre classics in the way that we think of the likes Blade Runner, Wrath of Khan, Back to the Future, Terminator 2, Aliens etc In 20-30 years I doubt many people will be like "oh yeah Iron Man 2!" whereas I could imagine someone saying that for 'recent movies' like The Dark Knight or Avatar for example.
We're a little premature here. I can't really vote until Avengers 3. However, I gave it an A for the work so far, which tends to range between B+ and A+ in my ratings.
I myself gave an A, just because of one thing - Loki. He was an awesome villain for Thor, but he was alright in the Avengers. I mean, the climax of the movie wasn't his defeat, it was Iron Man's sacrifice, in the Avengers movie too.... Spoiler: the ending of Thor 2 But after the Avengers, I had hoped they would've left him alone for at least a little bit. But now he's freakin' ruling Asgard....
When a character becomes as popular as Loki there is no way they'll leave him alone. I agree that it would have been nice to get something new, but sadly if people like something in one or two things they'll just keep using until people beg them to stop. I still like Loki, but I do think that if they keep using him he it will get repetitive.