Just got back from it here in the UK and...wow. I think this is by and far the weirdest narrative structure and editing I've seen in a mainstream movie. I mean, it had little to no pacing, stuff just happened, and while nothing happened for the sake of happening, there was by no means any drama in any of the action scenes save for maybe Steve breaking out the prisoners from the Hydra base. The random action montage after he becomes the cap, the Train heist and even the climactic battle all felt flat and uneventful.
I really liked the movie, but I agree those scenes weren't quite as thrilling as they could have been. Mostly I just blame that on the dull and lackluster score though.
Instead of lifting up the action (as the great themes in The Rocketeer, Superman, and even The Shadow did), the music just kind of laid there and didn't help out at all.
I would still rate the movie higher than Thor though. Thor had some cool moments, but the transitions and tonal shifts between the Earth and Asgard scenes were jarring as hell. I thought Captain America flowed MUCH better.