Took the wife and kids to the cinema to see this as a family treat. Was not in the slightest bit disappointed.
The film is frenetic, with a few slow but meaningful scenes, punctuated by action scenes with increasingly higher stakes. All the humour is there from before, and there are some nice soft personal touches - Hawkeye and Banner/Hulk especially.
Even better, the Avengers is global, with big action sequences taking place in Uganda, South Korea, and Russia.
If there was one niggle it's that Joss Whedon tended to shy away from realising consequence of potentially mortal danger.
I did, however, love the question they posed about the difference between being a hero and a monster - very well done.
The end climax in Russia was staggering and unexpected - the film constantly fights itself to create bigger and better dramatic tensions.
However, it was the fight between Iron Man and Hulk that really got me - not least because we saw the perspective - and fear - of the ordinary people caught up in it. And the scene where Iron Man and Hulk plunge through the skyscraper under construction - I could practically taste the dust of it.
A truly, hugely, ambitious film, unrestrained by imagination or budget.
And at the end, it closes the story to open what looks like it could be an interesting new chapter.
ADDED: Also good to see the way the film connected with the other recent Marvel films, not least bringing in supporting characters from Iron Man, Captain America, and Thor franchises -
ADDED 2: And - OMG - that was James Spader as the voice of Ultron?! Impressive.