Ignore uhhhhhhhhhhh789. This manga is not that bad. The storyline is good 6.5/10 in my opinion, character development 6/10 really good but its not shown that well as even though he explicitly states things his personality stays more or less the same changing only slightly, good overall character development though. Concept 5.5/10 good concept but overused. Art 6.5/10 good but not that good. Overall a little under 7/10 good but would not be my first recommendation. A worthwhile read if you are looking for something to read after reading better manga but can't find a good manga to read.
More biased personal opinion: overall 8/10 character development 10/10, art 5/10, concept 7/10, storyline 10/10