This is in my top 5 anime of all time. The first season lacks quite a lot because of the sub-par 3D animations, but the story is still extremely good. I personally loved the 1st season even with the 3D animations. If you can sit through those animations you will have a very enjoyable time. The characters are the best part of this anime. They are very memorable and are constantly changing. The second season is definitely the best and the 3D isn't completely cut but for the most part they go back to regular anime animations. A must watch for anyone who's into actionanime.