Right off the bat we start with a strong opening episode that tells us "this is no lighthearted adventure and all bad stuff happens". It's not a matter of being edgy, it's a matter of telling a story the right way! The dude has trauma, well justified trauma, nothing is wrong with the main character and side characters as far as I can see. If you want to be so picky about everything here then you might as well become a housemaid for all I care.
The story itself manages to do a great job at building suspense, expectations as well as subverting those expectations. It actually includes character development along with a little bit of world building that's done well. Or well enough for my standards (which are rather high (please ignore my current top scores, they are long since incorrect)). Also, the pacing is on point, so that's that.
Voice actors and actresses did a magnificent job. Not only do the voices represent characters well, they also match their looks for the most part. I guess that's what you would expect from studio with a good reputation. The animation is mostly on point excluding some out of place looking CG armor, but it blends in well enough to not distract your from watching. Sound design is also nice, it doesn't feel artificial at all.
TL;DR In short it's a really well done anime that manages to drag you into the world and feel sympathy for the characters despite being so dark and somewhat cheerful at the same time. You could describe it as life honestly.
