Sigh. Wow, how quickly things can fall apart.
Start off really hot - perhaps a bit on the generic side, but MC has real beef, and I was really enjoying how he flipped things around. There were some real surprises, like him being forced into situations where he had to slay allies from his first go-'round. That, I thought, was an excellent example of the 'consequences of change', something that isn't pulled off particularly well usually.
Then we have the mysterious hornless demon showing up, and Targ, whose smug face is just...so...goddamn punchable! So much face-punchage in my heart for that wanker! Some interesting developments with friends and foes, the truce between demon factions, the mystery of the old hero 'wanting to talk' with the old Demon King but then murdering the fuck out of him...there was so much that was actually kinda interesting!
And maybe that's the problem, because there were more loose threads than a tampon factory when the story closed. There was too much to focus on, and what we got was a One-Winged-Asshole out of nowhere with no backstory aside from a few wordless panels and a bad Harry Potter impression to explain his lack of horn. It seems patently obvious that somebody lost patience and told the author to wrap things the fuck up, because that's the only explanation for such a weak asspull of an ending.
95% of the way through things, I'd give it a solid 8/10. The last 5% tanks things horribly, taking it down to a shaky 6/10. It's like eating a good steak, only your last bite is all tendon and has bone chips in it anyway.