I will keep it short. Plot in this show is not unique. However it is OK to use it. Story in this anime is terrible. There is no real storyline so this ends up with confusing characters and actions. With a really good storyline that lasts 13 or even maybe 25 eps this could've been really really good.
The strongest point of this show is the awesome moments you get to see a lot. With the help of the beautiful OSTs those moments capture viewers heart. There were moments which made me cry in tears as well as scenes with badass action. Those moments alone are enough to make this show enjoyable which in my opinion is the most important thing for a work of fiction. Also in a few occasion it made me think deeply.
Overall a well wasted plot with a lot of great moments and ridicuolous stroyline. With a good storyline and a good MC who is not way too hesitant (this is a common problem with most anime tho), this show could've been great.
