THERE ARE A FEW SPOILERS IN THIS BUT THE FILM HAS BEEN OUT A LITTLE WHILE.
This is so far the best comic book film I have seen ever. I knew when Joss Whedon was directing he'd be the one too bring all the elements together in an epic film.
I really liked even though most of the characters have had their solo films they have introduced them like they never had been but didn't drag it out by telling everything (actually their isn't much from previous films repeated) that happened in the previous films. I liked how everyone had enough screen time too justify their spot in the film and characters like Hawkeye and Black Widow were shown as just as important as Captain America, Iron Man or Thor.
I thought it was a good idea too add just one main villain but with a giant army so it's not easy but it's not a lot of big villains that need screen time to develop their character.
The only thing that kinda anoyed me was how they changed the Skrulls to Chitauri. OK they've been aiming it more towards the Ultimate side but I just think that Skrulls are more connectible to fans as most comic fans know them and they added Thanos at the end who was involved with Skrulls.
I really liked the Hulk in this film best yet and I liked how Hulk revealed what was hinted at the end of Incredible Hulk that he could control his anger and that he was always angry.
This film has overall surpassed my expectations and is going down as one of the best film I have seen so far this year and being the highest grossing film so far this year and being the 3rd highest ever it shows that when you have a good lead up and a brilliant film you got a lot for your money.