It's deliberately looking like garbage. A show's opening and closing titles are traditionally emblematic, but here the closing titles are so bad that it's hypnotic. It's the worst-animated dancing in the world. Imagine geometric shapes being put through stretching, shearing and other computer image manipulation by freeware paint software. Imagine this in time to music. Now imagine these "shapes" actually being still images of badly drawn anime characters.
What's more, the opening and closing titles are probably the most entertaining parts of each episode. It's not a great show. It's just about good enough to get you to watch the whole thing, maybe, but then afterwards you wouldn't recommend it to anyone and you wouldn't watch a second season. You only watched it all because its episodes were only three minutes long. That's your best case scenario. The show has one decent joke, but two-thirds of its episodes aren't focused on that. However it has one key quality for a short-form anime, i.e. you'll remember it. Even five years later, you'll remember which one was Gakuen Handsome. It's the one with the pointy chins, the hit-and-miss attempts at parody and the all-narcissist cast of pretty boys.
1. POINTY CHINS
Just do a google image search. Yes, it really does look like that. The animation's on a par with the character designs, but the good news is that it works in context because the show's not meant to be taken seriously. Unrealistic character designs have been a thing in anime and manga for years, especially in shoujo, with a friend of mine referring to CLAMP's art as "the pointy chins of death". This show's just exaggerating that.
2. HIT-AND-MISS ATTEMPTS AT PARODY
It's a parody of shoujo manga (or boys' love simulation computer games, etc.) where the protagonist is surrounded by sexy boys. As it happens, the protagonist is male, but that's just a mild genre shift and shoujo manga would be fine with that too.
So far, so normal. What makes this amusing is the show's loud assumptions. On the one hand, everyone except our faceless protagonist believes that boys' love is a fundamental law of the universe. Boys are cool. Boys are handsome. Boys pose a lot and are liable to wear inappropriate clothing. Boys will look into your eyes and arouse sexual tension. Teachers and frighteningly young little sisters explain in a worldly fashion that it's normal for you to feel the warm, stroking tug of boys' love. They'll also be deaf to your attempts to protest otherwise.
The protagonist (Maeda) really is faceless, by the way. He has no eyes. His head's a blob from the cheekbones upwards. (This could be argued in itself to be genre commentary.) The show wouldn't be so funny if Maeda didn't think he was heterosexual. In fairness he's usually immune to his classmates' antics and at such times is merely being the universe's straight man, but every so often he'll turn into the blushing, maidenly heroine of the romantic genre that's currently being parodied. This is quite a good joke. The ep.7-8 two-parter is amusing, for instance. In a different show, it could have been excellent.
3. ALL-NARCISSIST CAST OF PRETTY BOYS
Unfortunately the cast is dull, as is most of what they do. They're parodies of a character type that's already fairly flat. They're smug, silly and all too handsome to have much of a personality. That's true even of the ones that theoretically should stand out, e.g. the rich one who takes a part-time job to try to understand lowly commoners. They're all liable to do character-breakingly silly things (e.g. turning up to a date in only a sumo wrestler's loincloth, although in fairness this is funny) and are all basically superficial, self-obsessed idiots. I didn't believe in them as people and I didn't believe that they'd do what they do.
That's fine, up to a point. The show's not going for realism. However the upshot is that this is a show that doesn't really have any characters, as I understand it. It has a single character type, which is expressed collectively in a gestalt sliding scale sort of way. In fairness, though, Maeda is different from the others (if entirely passive), while his little sister stands out simply because being his little sister redoubles the punch of what's otherwise just the show's standard joke.
Apparently the smartphone game's good, though. I don't hate this show. I think it would have been possible to turn it into something pretty good, while even this daft, throwaway version is watchable in an "only three minutes" way. It's memorable, in its gleefully stupid way. It's different. It's the only show I've watched recently where bad voice synching felt like part of the joke and made me wish they'd done it more often. However it's still too liable to confuse "silly" and "funny", while quite a few episodes needed to work harder at coming up with satisfactory punchlines. It's extremely mixed, which averages out to "average".
"I am perfect, so why did my bread turn out this ugly?"