Hmm. It actually kinda surprised my why this series was rated rather average, and after digging through the comments (that for my sake, didn't contain spoilers) it seems that the complaints are:
1) The concept is not entirely original.
2) The villain (I assume Nightingale) is rather cliche.
3) Main character's motivations are inconsistent.
This might make me sound like a stubborn stan who refuses to accept that the manga I like has flaws, but I disagree with some of the above.
1) While the concept of "Select people have superhuman powers that, at times, are reality-bending" is pretty common, the idea of them being "reincarnations of past famous figures" is rather unique. I guess the closest thing to this manga's power system would be shuumatsu no valkyrie, but the story is utterly different.
2) The villain is absolutely an overdone one. It's basically a lazyman's answer to the question: "Why do the goons stay with the obviously evil guy (except for obviously evil reasons)?". Overall I'd say that I would agree it's a weak point of the story. It's bizarre that neumann wasn't able to predict this from happening in the first place.
3) The main character's motivation was originally "Get all the talents and become the most talented person alive", which is rather straightforward. Now the main character is what can only be described as a selfless individual who'd willingly sacrifice his life to save all of humanity. While this is a dramatic change, I don't at all find this unnatural. The main character's motivation was originally to be as skilled as his older brother, and functions mostly out of spite. Now he knows that his brother was a returner and that the entire world is getting nuked, it makes perfect sense why he's no longer hellbent in gathering powers.