Quick thoughts:
I'm surprised to see Sam Jackson playing Nick Fury so straight. I always figured he'd be more like Millar and Hitch depicted him in The Ultimates, kinda jovial and whatnot. The press conference bit was awesome on many levels. Mickey Rourke was hard to hear with that accent, but his performance seemed appropriately menacing. Black Widow looks really tough and determined, no BS damsel-in-distressing; good stuff. The Iron Man armor looks sleek in this sequel. Didn't see much of Sam Rockwell, but what I did was very entertaining. He reminds me of a funny Gary Oldman in this. I see why he was considered for Tony Stark the first time around. War Machine...well, it looks pretty awesome. I'm assuming from that shot around 3:26 that Rockwell's Hammer character customizes the Mark II armor with all those weapons to get to the War Machine we're all familiar with?
It looks great. I'm interested in seeing how the traditionally villainous Justin Hammer comes in cahoots with Rhodes and the military. Favreau seemed to be looking at The Empire Strikes Back when he made this, a favored template of many filmmakers for good reason. This came off as more bleak and serious than the last film, and the story doesn't seem to be running away from the critics who said the first could've done with more self-reflection on Tony's role in the global situation.
All in all, exactly what I wanted and more. Can't wait to see this.