We saw this one tonight and it's quite good. I don't know the original story at all, so I went in fresh, but the story held together, the FX were excellent, acting was as good as it needed to be and it was enjoyable. I'm not a big fan of 3D, but at least it didn't do much harm (although I do think that it reduces the sharpness of the image).
3D aside, I really liked the 40's Moderne, sepia-tinted art design and the ernest-ness of the WW II era plot. The Nazis spit out their evil words and get down into occult science, and general Nazi weirdness. Captain America saves the world for goodness and the American Way. It's definitely a weekend popcorn movie, but plenty of superhero movies are much worse.
BTW, if you see it, be sure to endure the credits, because there's a trailer for the 2012 sequel. A couple parts of the movie are setups for the next movie too. The credits go on forever, because there must have been about a thousand people doing digital imaging, FX, etc.