Well.
I eventually did finish this game. Normal difficulty is pretty easy. I never lost a fight that the game didn't force me to lose in the first place. Said fights soured me on the game quite a bit tbh, I really hate those sorts of mechanics... though how much I hate them depends on a lot of factors. From the standpoint of objective facts, the forced to lose fights are extra bad in this game due to the fact that you can't really heavily stockpile on consumables, and some consumables aren't purchasable at all. The regen consumable (which is equivalent to Nymphoria's lvl1 healing skill) and the barrier consumable, which basically gives you 100 extra HP whenever you need without consuming a turn, never show up in the crafting list.
And they're really, really useful consumables, especially if you want to do low HP shenanigans to take advantage of the attack bonus and the SP regen bonus at Strip lvl 2. It's not something you need to do much of on Normal, especially after you get your hands on the SP regen hat and the SP pool reaches ~200... but I imagine that it might be relevant for anyone wanting to try the harder difficulties?
Not sure why you'd want too though...
Moving on, I can kind of see why that one person compared this to Celesphonia, as there are some very superficial similarities I guess... but if you DO compare these games, mechanically speaking, Nymphoria is a way, way, waaaaaaaaaaaaay worse game. You only get one action per day. The amount of H-events you have access too besides the defeat rapes is tiny and they're all entirely linear. The sex stats do almost nothing except for the lewdness level which unlocks public masturbation at lvl 4 (not 3). Virginity is irrelevant and never actually mentioned to the point where it's questionable if any of the girls are virgins before this whole mess started. All non-rape events are linear and tied exclusively to story progression and nothing else. The game also kind of pressures you into getting said events because they give stats and you do need them.
The worst part of the game, tbh, is the fact that you have only one action per day. This means that you can choose between seeing an H-event, or fighting. This is problematic because you HAVE to fight no matter what to keep the peace value up... and you don't have an outlet for accumulated lust outside of the H-events until you get public masturbation. This makes managing time tedious, and later on, you end up with situations where you have H-events available, but there's no battles available for you to accumulate lust with, so you can't see them, which leads to just passing the day sleeping. The reverse also happened a couple of times, where I had battles to fight through, but no H-events to use the lust with, but by that point, at least public masturbation was unlocked.
All in all, it's a fairly decent game, but I can't call it a great one in terms of mechanics. Mileage will obviously vary when it comes to other things.
I like the art well enough, even if it's not a favorite art-style for me. The scenes themselves are pretty good, and some go really nicely for me because they have actual cervical penetration, which is actually pretty rare to have shown explicitly the way this game does. The overall story is pretty meh though. There's nothing really that makes it stand out to me, and it gets a bit too ridiculous at times. I get it that it's meant to ride on transforming hero/heroine cliches with a lewd bent, but it kind of falls flat for me on multiple occasions. Also, the fact that all three girls are distant cousins with nutso grandparents is just silly...
Lastly, if there is one thing that's absolutely annoying about the translation that I genuinely think should be fixed, is the fact that the evil organization keeps having its name translated in different ways. I dunno if that's some kind of problem with the original text... but it's called Masteron, Mastaron, Mastelon, Mastalon, Masterlon, Mastarlon, and there were a couple of other, more rare variations too that I don't remember exactly...