Well, I have to say that I actually did enjoy a lot this series.
It starts really strange, so don't worry if you don't get whats happening in the first few chapters, I actually was about to stop watching it which would have been a huge mistake. I never thought I was going to enjoy it this much. I read in a review that the first 15 chapters were the good ones and that the rest didn't matter. I personally feel the exact opposite. I thing you need to give the series a couple of chapters before you really get into it. One of the aspects I liked the most was the animation. Maybe some people don't like it because it's really odd... however this is exactly what I liked, It is completely different to the animation you normally see. Fighting scenes are really well done and character development is also good. Both the Opening and the ending are cool (specially the opening, which I also found strange.
Apart from all the technical aspects, the story is really interesting although I found some of the quantic explanations rather boring (maybe physicists like it). Anyway, I don't know if you'll find this comment useful or not.... I just wanted to tell you that I liked this series and that I think anyone who likes anime would find it pretty enjoyable.