This is definitely one of the best use of CGI in anime to date. The camera angle when Dia is getting chased by the dog like lunarian feels like you are together with them in the scene, I mean you can feel the tension and it reminds me of the raptor scene in jurassic park.
Too bad though, a 12-episode series is definitely not enough to develop all the characters they introduced, most of them are interesting in their own but without proper focus then they will just become another face in the background. But what they did with Phos is amazing, she (well the characters look like girls to me despite them not having gender lol) turned from a useless brittle rock that always needed saving to a badass fighter that saves others, though I can't totally be happy with that because I like her bubbly personality more than her cool and level headed self.
I can agree about its ending, it ended with many mysteries still left hanging (probably for a shot at season 2, but we can only hope for one lol) but still a must watch anime from 2017.