just saw it a few hours ago.. preliminary thoughts-- (spoilers)
one of the best experiences I've had for these kinds of films. Lots of stuff for the principals to do, nobody just arbitrarily sidelined..
--The one stunt that felt a little "off" was Thor attempting to lay out Cap, which.. laid out everything around him.. absorption notwithstanding, traditionally Cap can still be slammed by the general impact.. But at least the Big 3 got to have their 'misunderstanding' battle before the bigger brouhaha..
..Pleasantly surprised at Pepper's appearance, I had heard at one point she wasn't involved.. Glad to see a brief glimpse of Iron Man underwater, I'd like to see an entire water sequence in a future film (Atlantis, maybe, and the film involves a sea prince..)
..Scarlett in her Widow catsuit got more than a few catcalls..

.. Tony's 3rd act transformation was cool.. didn't know what the bracelets were for at first..
..I wanted more Hulk, but I suppose the 'less is more" approach probably helped.. I also appreciated how he was allowed to go nuts on Loki.. (the segment could have been stretched out, though, heh..)
Memo to marvel: Keep the talent that wins the games for you! Bring back all the actors and Joss Whedon as writer/director..
At last, a cosmic villain is revealed for the next team-up feature.. wonder who will play him on film.. (I imagine "anyone" could have done the cameo..)
The post-post credits epilogue-- classic!