I posted a review of Avengers Assemble back in May when I saw it in 3D on the big screen.
I have now re-watched it in 2D on the small screen. And it's still great!
Well done to Joss Whedon and to the cast for a great ensemble performance (no pun intended).
In May it was at position 31 in the IMDB Top 250. It has since drifted out to position 100. Now there are two comic book movies ahead of it: The Dark Knight and The Dark Knight Rises. If it slips a few more places then Batman Begins will pass it as well.
When you're watching it, stick with it until the credits are over. There is a small reward for sitting through them all.