I fail to be impressed, even less so than for each of those characters' own movies. It's like "ok let's bring half a dozen dudes together and have them do generic action stuff and a buncha one-liners to each other YEAH SUMMER AWESOME MOVIE BEST EVAR!!1"
Or not. It'll be some kinda clusterfuck with half a dozen lead characters each vying for screen time and impressing the audience with one-liners (where Stark will most likely get all the attention) and dumb shit. Like X-Men, where Wolverine got slid forward to become a main character for example.
I can't see this becoming anything else but an okayish, thirteen-in-a-dozen generic superhero movie with too many lead characters. Visuals are underwhelming too, at least in this trailer, and (also in just this trailer), story seems non-existent and unexciting. I mean, what's the story at all except for an unnamed (or even directly-referred-to) baddie and an unfunny slapstick half-a-dozen-dicks-and-a-not-too-hot-chick movie?