This manga is insane and amazing.
Story - The story is strange and will not go exactly where you expect. When I first started reading, I thought he was just doing a mecha for fun but now I realize that he is trolling us really hard. This series has all the standard mecha features, but everything is twisted and insane and delightful.
Art - The art is great, even if it's a little different from his other works.
Character - The characters are really fun. I can't say that there is lot of what I would call actual character development, but they are
all interesting and weird. And the love triangle between the boy, the girl, and the boygirl that transforms, somehow, into a love triangle between a boy, a boygirl, and a gigantic monster made of space goo is just....I don't even know. I don't even know.
Enjoyment - There are plenty of epic space mecha battles for action, and then also details of the really strange sci-fi setting, not to mention the mysterious past. It's very enjoyable to read.
Overall - If you already like Tsutomu Nihei stories I'm sure you'd like this one as well. And if you like something really weird and different, that includes a gigantic monster made of goo who behaves like teenage girl, then seriously take a look. Really I don't even know what to say about Shiranui. Like I really thought I knew what he was doing with this story and then she showed up and I didn't know anymore. Anyway go read it, it's pretty great.