Wow, what a fantastic series. This anime will definitely leave a massive impression on you if you give it the time and chance. I almost gave up straight after the first episode due to not being able to follow what was happening, but in retrospect this is necessary to allow a brilliantly constructed story to unfold to a climactic and satisfying conclusion. At first some of the characters can seem fairly annoying when looked at individually, but their personalities and chemistry makes the group cohesive and vibrant. This is the first sci-fi anime I've seen and the time travel concepts and the physical laws imposed are thought through in great depth. I love how they relate to modern physics at some points to add depth and realism to the plot. All in all... Great looking anime, quality soundtrack and voice acting, and amazingly written story.