This manga has a lot of interesting aspects that work quite well together. Firstly, the basic premise of a robot protagonist doing his best to blend in unnoticed with humans while having to deal with various problems that only robots have like charging and maintenance is incredibly interesting. The writing also does a good amount of showing the internal thoughts of the protagonist, which are very logical and contrast in a generally amusing manner from all the humans around him who are often quite emotional, but at the same time don't feel completely cold and seem to have some level of humanness to them. This results in some great comedy, but also allows for a lot of good character and relationship development. The highlight of this is the heroine Hirose, who is incredibly likable and has a decent amount of depth to her. The robot aspect in general also feels very well done with things feeling like they're being properly explained for the most part and it getting quite deep into the hard sci-fi aspects. This is especially prominent during the action scenes like robot battles where things often get incredibly complicated and heavy on tech, but still manage to flow well and be really exciting and interesting.
Unfortunately, all of these strengths only last for about two thirds of the manga. After that the blending in aspect gets dropped and in general the comedy disappears, leading to a much darker tone. The plot ends up going in directions that really doesn't treat any of its characters well. Some characters end up getting completely screwed over by the plot, in some cases in ways that feel completely unfair and unnecessary. Some characters that seemed likable have random heel turns which are equally annoying. And some just end up being way more lame than they should have been. The plot itself becomes overtly crazy. The harder sci-fi aspects are dropped and characters just start getting arbitrary supernatural powers. And while the ending does finish essentially all the important plot threads, it doesn't feel satisfying at all as it feels that it does this by throwing away pretty much everything it built up over the course of the manga. It also doesn't help that this entire last third happens in an extremely rushed manner that just makes everything so underwhelming.
If you've read another relatively popular manga by Boichi, Sunken Rock, it isn't that bad, but it's pretty close, and I think close enough to give me an impression that this guy while great at coming up with concepts for manga is terrible at ending them. Still, a strength that does remain consistent from beginning to end is the art, which is excellent with good designs and an elaborate art style for both characters and machinery with good range in terms of being able to convey action, horror, and comedy all pretty well.
