I finished undertale with first a neutral then a pacifist run and I thought it was pretty neat and a liked a bunch of its characters but its far from perfect, some characters are awful people with the game refusing to acknowledge it, the morality handwriging gets really obnoxious after a while (especially if you do 2 runs like me) and the fandom is cancer.
The fact that the game treats self defence as a "sin" I found to be especially offputting. You're treated s a villain for not actively trying to befriend lunatics that attack you on sight and in the case of undyne you're treated a villain for not going out of your way to save the life of someone who 3 seconds ago was trying to murder you and rip your soul out. The writing while certainly "emotional" completely lacks nuance in this regard.
This is also especially annoying when facing Asgore. Asgore is a serial killer of five seperate children that he actively sought out to murder, and you HAVE to forgive him for his crimes, but god forbid you kill even ONE monster (in self defence no less), because from that point on you're irdeemable and literally have to reset the entire timeline because your soul is tainted forever otherwise.
Character wise I really like Papyrus and Metatton because of how audacious, egotistic, determined and confident they are. Metatton radiates that Roger Smith/Bender/IASIP energy where the bigger asshole he is the more likable he becomes because of how confident/determined he in what he does and Papyrus reminds me of Kronk where he fails at being evil in a way that you can't help but like him. (Also being confident and audacious with a huge ego helps.)
However, characters like Aphys (and both because how the game treats her and how the fanbase treats her) straight up pisses me off. Aphys is literally the Josef Mengele of the undertale universe while also being the personification of a redditor, she horribly mutilated a bunch of people leaving them in perpetual agony, locked them in the basement, lied to their families, and spends all her time reading manga and talking about japanese visual novels on twitter using slang fit for a 14 year old girl, while also acting like a shy easily embarassed "uwu" wallflower.
To top it all off in the "good" ending where you convince her to tell the truth she goes "I can't keep doing this to myself, I have to tell the truth." She doesn't say "I can't keep doing this to THEM" she says "I can't keep doing this to ME", as if SHE is the truth victim of all this, not the people who she has kept locked up in the basement in perpetual agony for all these years, the only thing she cares about is what everyone will think of her.
In the good ending she gets to be with her lesbian lover and in the "bad" ending she hangs herself, which should really be inversed. Speaking of, if you want to get the good ending you have to play matchmaker for 2 seperate gay couples.
Also as a side note, the comedy in the game is really good. There are a lot of shit jokes, but also a lot of really good ones and its one of the few "comedy" games that have ever made me laugh out loud. I think that for every person that plays this game there is at least 1 joke that will make you laugh out loud.
All in all, the game isn't perfect, but nothing is, the morality can get obnoxious, but (some of) the characters are fun, the soundtrack is enjoyable, the comedy is scattershot hit or miss (with a decent ammount of hits imo) and while the fanbase is total cancer, I don't regret playing it.