I actually like Cap's type of humor -- it's more dry, less snarky than, say, Tony Stark, but that works for me. But I agree that most of the humor in this movie didn't come from him; it came from Sam and Natasha.

Other people have made the point that Captain America's real superpower isn't being a super soldier, it's how he inspires other people to do the right thing. Like the SHIELD agent who wouldn't enter the launch codes, even at gunpoint, even knowing that it might not make a difference in the end, because he was following "Captain's orders." I loved that moment. And it happens in the other movies, but it's made really clear here.