Spoilers
Enjoyable (and a true geek fest).
Hawkeye switching sides was unexpected but then the trailers all show him back on the good side at some time so that hole plot was kinda wasted. Same thing with Hulk catching Iron Man from the trailer - I knew it was coming all movie long and that something so near the end of the movie was shown before the movie came out made that scene less significant imo.
And I always groan whenever they do the forced Stan Lee appearance - something I wish they'd do at the beginning of the movie to get it over with as it pulls me right out of the movie experience every time.
I know I'm probably just supposed to sit back and ride with a comic book movie - but the death count of Manhattanites must have been staggering.
Acting - Downey was perfect (and I look forward to the Blu-ray to hear some lines that I missed because they came so fast and audience laughter muted them). Ruffalo was surprising - so very very good and worked well with/against everyone. Bana/Norton who? RDJ & Ruffalo really shined (probably because of the comedy they oozed - which should have come from Brer' Hawkeye but he had to be all dark and edgy

).
The story worked for the movie but it really was a lame plot. Make the heroes not work together by getting them all together. Yeah - great one Loki.
And I guess Whedon didn't like the 'Avengers Initiative' as he tanked it between movies. This actually worked out all right though.
Another surprise - I would have thought that SHIELD lady with the black hair would have been the one to 'follow orders' and fly the nuke. (which begs the questions - who are these World Security Councilors that can order a nuclear attack on NYC? HUGE bonus points on Jenny Agutter

being one of them tho! )
As corny as it was, the words "to court death" being uttered as Thanos was intro'd was nice (and something only a geek would ever get).
I'm a huge Avengers fan. I have every issue from #1 up to Bendis taking over. Seeing these characters on screen - and seeing them together - was something I've been dreaming about for 35+ years.
This was a good film - but the book was better.
And saying that - this was a film and the film gets a 7.
One final thought -
replace the words "King Kong" with "giant flying alien fish things" below...
