There's a lot that's really good about this manga, but it was seriously lacking in a couple ways. The general premise with powers, enhancements, and such works really well and the use throughout was pretty clever and there was a good amount of variety to things. The humor especially was really solid throughout. The four main female characters are also pretty great, especially Koyuki, and for side characters most of the side characters are decent as well. However, Umehachi is incredibly weak for a main character. He doesn't even feel like one most of the time. In the end, how the entire story seems to pretty much go over his head seems a bit disappointing. Furthermore, this also adds the issue in that while I really did want to the relationship between Koyuki and Umehachi to take off and do well, and hence the ending in and of itself was good, the build up to that felt tremendously weak. There wasn't really any instance where Umehachi excelled or anything at all that could be seen as pushing their relationship from Koyuki sticking to him for his power as it in the beginning to actually being in love with him. Rather, even in the end it isn't completely clearly established that she really does and wants to be with him, she just sort of does, which all around feels kind of weak, even though it is a happy ending. The art was really good. 

tl;dr: An interesting and amusing set of stories with a cast of power users, but a really weak main character that leads to a somewhat disappointing ending.