As a person who watched a recap on this manga till chapter 15 and then read till chapter 35(using Google translate for the latest chapter with out English), I think I can give a fare review. For the people who left many comments on this manga clearly without reading at all, this is actually how it is.
It's not a harem and I don't know why it had that tag. It has multiple female characters that interact with the MC but rarely at the same time and in general they don't show that much romance in the manga. While he is edgelord at times, they seem to have stopped that after he went back in time. He did massacre his entire village and tormented the person who raped and killed the first person he loved, but that was honestly kinda deserved and far less horrible than what the MC of Redo of Healer does. He stays fairly innocent besides that one slip up of complete vengefulness. Don't worry he died and the time reset so it didn't happen. As for the Re:Zero, I've never watched or read it I couldn't say how similar it is, but based on what I've seen, probably not that much.
Now for my actual opinion of it, I'll avoid describing what happens in the story to avoid more than one spoiler in this comment(but are probably some more). It was great at the beginning, but then after a 100 year time skip to the past he now has to worry about protecting other people to prevent the world from getting destroyed. I just felt this was a major shift from how the story was going before. But the biggest problem was how stupid the MC was in the during his time in the past. He wasn't actually that stupid, he just missed one crucial advantage he could have by being able to save and reset when he dies. He can off himself when ever he wants or should, but he doesn't! That's the whole reason he even got sealed during this time, he didn't think to snap his neck to get out of the situation. Now I would be more angry at this manga if it ended at chapter 34, but chapter 35 relieved some of my anger.
Anyways 8/10, just wished it made some better decisions. Honestly hope it goes strong.