The overall reception for this anime has been simply astounding for me. I wouldn't put this in my top ten for 2011, or even consider it. I don't write much, but here's some basic problems I had with the anime by section.
Story - The story did a good job at making sense, which is hard to do in a time travel scenario. However, making sense does not automatically make something good. Also, the time travel mechanisms aren't as original as some may say. The idea of sending messages to the past has been used in a movie like Deja Vu, for example. The idea of unavoidable events in the future have been used by other anime such as Madoka and Higurashi. The end seemed to be TOO happy as well, it didn't seem to fit with the rest of the anime. Overall, the story seemed to be paced improperly, somewhat derivative, and I never found myself really engaged in it.
Animation - Not too many complaints with the animation here. Character designs are nice, no real eyesores anywhere.
Sound - I never pay attention to the sound in almost any anime, don't have really anything to say about this either.
Characters - The characters are definitely stronger than the story, and are the main reason I decided to sit throught the whole thing. Although the point of the characters was to be eccentric, sometimes I felt that the insanity of the cast was a bit too much with a lack of a real "normal" person to keep their quirks in check. For example, Okabe does things socially inappropriate things all the time, such as groping Ruka in one scene. No one really reacts too strongly to this, because the rest of them are slightly messed up too. It just seemed weird to have a whole ensemble of crazy people doing crazy person things. I do have to give Kurisu credit, however, for being one of the least bad tsunderes I've ever seen, although I still don't like her because she's still a tsundere.
Overall, I have always been surprised by the absolute love of this series that many people have. I was never deeply affected by it, and although the technical aspects were good, I felt the story was lackluster, and the characters weren't too outstanding.