First of all, let it be known that conceptually, I love this series. The action was great, the animation was incredibly interesting, and the psychology was complex and interesting. However, in my specific case, it had one fatal flaw that just ruined it for me, and that was that it wasn't very involving. The nature of the story was one such that the protagonist had to be ordinary and that not enough of the plot could be revealed to make it involving. For these reasons, I certainly can't blame the producers -- they played to the story's strengths, and did a great job on them. The weaknesses just hit me pretty hard, which may be my own fault rather than theirs, but that's how it went.
As much as I liked the complexity of the story, the animation is probably what interested me most about this anime. Every alternate reality entered throughout the anime (and there were many) was built from abstract art, which not only made for a surreal effect that drew you into the atmosphere, it just made the whole thing more visually interesting. One can imagine the animators having fun putting the worlds together, and the complexity and impossibility of it all adds to the chaotic tones the witches and everything surrounding them are supposed to invoke. On a less serious note, I also had fun identifying the art where I could, as some of it is pretty famous (although the only one I knew by name was Picasso's Guernica).
This is the main problem I had with the anime. I found the characters fairly archetypical and often hard to relate to. Again, on some accounts I see the producers' rationale for this -- Madoka in particular is specifically supposed to be ordinary and is supposed to have a relatively comfortable life, and the rest of the characters are largely the same, a fact which is supposed to underline the inherent tragedy of the premise of the anime. This is all fine with me, but it makes the whole thing a little less involving, which in my case led to a sense of detachment from the characters that made me care a little less whether or not they died -- which, unfortunately, is a very important part of the series. Perhaps I'm just desensitized, though.
Again, I like this series conceptually and would love to give it a ten, but it just didn't draw me in as much as I'd've liked. Perhaps I just had it overhyped for me, but in my opinion it could have been better.