Even though the story isn't finished yet, this is quality. The backstory within this anime is probably the best backstory I've seen within anime, very detailed and it explores why the main antagonist became the way he did. The backstory paves a way as a challenge towards morality, which is interesting and how reckless we can be as humans, jumping to conclusions and how we can behave like monsters.

The story nicely ties in the idea of duality, with our main character developing because of his other half, Claire, as he's forced to submit to his environment and drop the morals he long wished to hold on to. The designs of the monsters are really good, and although Claire can be quite psychotic, she is definitely one genius, which is a part of her you cannot hate, and the protection she gives to the protagonist.

Fight scenes are really good, however the story can be confusing at times, and it is quite easy to lose the plot but overall a good anime, mainly built around an excellent backstory, and portrays ideas of how far we go to claim things we believe is ours in this case it was our protagonists memories, who is quite similar to eren in a way.

Also the abilities and power scales are great, so far getting only a few glimpses of how overpowered our antagonist is, and our protagonists Shuichi and Claire.