Well, the concept of reuniting all these superheroes was inevitably going to stir humongous hype.
It was my 2nd most awaited movie of this year. Personally, it turned out better than my expectations. It's one of the best action fest I've seen - especially in 3D. There are a number of reasons why it's successful:
1. There are few quality superheroes movie and this one definitely wasn't a dud. At the very least, it was highly entertaining. Coming from Marvel Studios, it's perhaps their best attempt.
2. Their decision to prime action instead of conversation and character development is correct. Don't get me wrong but all these characters - Thor, Iron Man, Hulk, Loki, Captain America - got a solo movie where there were loads of character development and history. Sure, certain of those movies were either great or barely average but it will have been a waste of a time to re-present deeply all those characters.
3. The cast is aptly chosen and all of them blends well. Ruffalo's restraint & Downey's narcissism are perfect. Even Capt. America's character which was awfully boring in his Solo movie got me a bit hooked.
4. At least, all the money spent on this big-budgeted movie ended as a full-on blast action. It wasn't boring like Transformers, 2012, Narnia, Battleship, Superman Returns ect...I'd give credit to the makers that even if they didn't make a masterpiece in terms of story, I didn't regret my money a single bit.
5. They are now pretty much setting a global mood for Marvel Superheroes. One where it's glossy, funny and full of extravaganza. And it's nice to find similarities between them. Especially at the ending. We gotta admit that for a movie with little character development and predictable story, it has the heart to make all of that work.
The only flaws in the movie is that:
1. It lacks any kind of novelty in the plot.
2. The villains - other than Loki - deserved more emphasis.
Otherwise, we should appreciate it as it is and for its epic entertaining value. We are going to ruin the whole experience by being over-critical.