From what I can presume, UQ Holder is some sort of sequel to Negima, that ridiculous ecchi harem manga with lots of distasteful stripping and panty shots and all kinds of fanservice. Which made me avoid it even until now, because I couldn't stand supposedly great manga that can't help but ruin their stories with terrible ecchi.
Couple of weeks ago, I discovered UQ Holder, recommended to me (didn't know about that whole Negima relation thing for a time). It was pretty nice. I would rate it an 8/10 a couple of days ago. A tale of dreams, adventure, and friendship. A standard shounen and a
pretty entertaining one at that. There were a few times of fanservice but it has even less than other standard shounens.
A few times there would be a couple of references to Negima which, while I couldn't relate to, I could tolerate because the story was fine even if you didn't read it.
Then when the manga was nearing the hundredth chapter, the author decided to just ruin all of that greatness and bring Negima to ruin this one. Before, there was practically no harem; only one, maybe two characters were being teased with the main character but just barely and not that much.
But no, suddenly, the author simply decides to take pretty much almost all of the female cast and make them suddenly attracted to him even when they showed little to zero feelings for him before, then give the readers a couple of characters who people have no attachment to because they weren't (or barely) in the story before and shove him into the shoddily made harem too just for the hell of it.
Oh, and made sure to have a lot of fanservice and nudity; I can tolerate some from time to time in other manga, but it becomes ridiculous when you get a reunion with this character in the early chapters and make her run around fully naked, and extremely ridiculous where characters are going around and fighting each other or their enemies while fully naked like the author doesn't care anymore. This kinds of situations are what triggers me when I read manga; this is the reason I dropped Fairy Tail and Tokyo ESP, seriously, which were both otherwise great shounen manga before they decided to go ridiculous with nudity and fanservice.
Well, aside from the forced sudden harem and the sudden surge of ridiculous fanservice, they also decide to bring Negima into the story by simply just shoving a lot of Negima characters into the story. Characters who only people who read the original manga will appreciate, leaving those who read this manga first in the dust. They simply keep introducing character after character who apparently is in the original series.
I read a couple of reviews for this manga that were submitted a few years ago, oh, and how wrong those people were. "This is not Negima 2.0", "This is an almost completely different manga". That was the case back then and I enjoyed it until we reach around a hundred chapters when the author decided to Negima-fy the manga. That would be a good thing for those who liked the original series, but not those who grew to love the normal and enjoyable adventure shounen that was UQ Holder.
This would have been a pretty high score before the storywreck a hundred chapters into the manga, so I'd simply just average it out and give it a 5. I'd probably still continue reading it because I have grew attached to a couple of characters to drop it at this point. But if you're someone who is interested in this manga and doesn't want fanservice, you probably shouldn't bother. You'd grow attached to the story and the main cast but the author will decide to ruin it a hundred chapters after. Likewise, if you're someone who wants hardcore fanservice shoved into an action shounen, you'd only get to have that a hundred chapters after because the manga barely had any of that beforehand.