To be completely fair, by ecchi/harem standards, this is a well written show, unlike the rest of the genre. I started watching it with pretty low expectations. After reading the plot, I thought this was going to be that type of show where the MC is busy with the girls for the whole anime, so the storyline is grossly neglected. This anime is exactly the opposite. No description would fit this better than "Come for the boobs, stay for the story"
Story: 9
The highlight of this anime is definitely the narrative. As I said, instead of the usual ecchi priority list of boobs first, story later (or never), Shuumatsu no Harem has a very strong central plotline, focused on the MC genuinely trying to solve the mystery of the MK virus and the disappearance of his love interest.
Art: 8
The animation is solid. Of course, since it doesn't have any ambitious action scenes requiring lots of work in the animation department, it was kind of expected to have good quality overall. Even though the story is set somewhere in a near dystopian future, not a lot of futuristic designs are explored. But I have to say, the character design is done smartly, so that the viewer would easily remember the important characters and tell them apart from the rest, since so many characters (especially supporting) are introduced all throughout the series.
Sound: 7
The music was nothing special. It fit the theme and it did what it was supposed to do: make me skip 1:30 min at the beggining.
Characters: 8
A lot of focus is on the characters. They are explored pretty well in 11 episodes and it is clear that even the characters who weren't really explored here have a backstory and a reason for their actions. The foreshadowing is done pretty well, making you question each character's true intentions and purpose. When it comes to the erotic part, obviously both the male and female characters fit in a strict anime trope (which I do not particularly mind, but it is not a plus either): the cool, low-key misogynistic playboy, the nerdy bullied boy turned pervy sex lord, the pure MC who is not interested in other women but his crush (hear that Peter Grill?), the tsundere girl who starts warming up to the MC, the secretly-evil cute airheard, the busty sadistic bisexual MILF, the cute jealous E-girl with an inferiority complex, and so on. And of course, boobs and nudity everywhere, because at the end of the day, it's still supposed to be an ecchi series.
Enjoyment: 8
As a non-straight man, I can say that this anime was pretty enjoyable. The mystery plot keeps a certain group of people hooked, and the anime titties keep the other kind of viewers entertained.
Overall: 8
A solid series. I do not understand why it has such a low score. Compared to a lot of the 2022 spring series, it's actually enjoyable. Good story, nice character development, decent animation.
Go give it a try!