Sorry its a little hard to explain but for me its less about the category and more about the copy and paste characters being the problem, most(out of about 150ish games i have played i'd say around 90%) VN characters are exactly the same so for me how good the game is going to be comes down to how the story and situation can stay interesting despite the reused characters, with school slice-of-life obviously lots of standard situations from that category are going to be in all school slice-of-lifes and i already know how the characters will react to them so a very large part of the game is(for me someone who playes way too many VNs) going to be boring repeated content which i really dont want to waste 60-70hours playing just to see what is probably just going to be a pick the girl ending.
When picking VNs now i try to go for ones with a good story which is effected by characters as little as possible, ones with unique situations which would force even copy and paste characters to act differently or games with choices that matter and produce interesting endings.
Please note i am not saying this game is bad as i have never played it i wouldnt know but it dosent seem like it would suit my tastes in VNs.
Warning, some spoilers regarding mechanics (but not plot, hopefully).
So for one I can assure you this has no "pick the girl" ending. Yes, there is an ending for each girl but for one, but those are after long and separate routes for each girl (think first Grisaia, if you played that) and then there is the true path which is even longer. The common part of the game (from which the routes split at different points) is also constructed in an unusual way, where while the overall structure stays the same between playthroughs, there are events that happen at random, making it so that even on repeated playthroughs you are going to see fresh content (in fact, there is a reason to actually replay from the start after every ending instead of just loading save states, but that goes into spoiler territory). Obviously you can use skip to pass what you've already seen and just focus on the new scenes.
The game also features multiple unusual systems (which are optional if you get tired of them), like battles for the characters battle-ranking (non-interactive, but who fights who and when and with what is random and can be influenced in various ways, you can also aim for the top yourself), very fun baseball practice arcade minigame you get to play periodically, a tactical minigame for the actual end-of-the-year baseball match and some more random fun stuff. And one of the DLC characters has *shooting* in her route..
It also has an astounding amount of replayability for a VN, I think I genuinely played through the common part in full for each route I did (minus skip on seen scenes, obviously) and each time it was fun and I got to see new content. In fact I'm still unsure if I saw all the scenes on the common path.
So if your worry is that the game is going to be "generic" they it's probably unfounded. As for characters, I'd say they are good, though the again, I haven't played 100+ VNs, so your experience may vary. Though I think this game is considered a classic for a reason.
One caveat that I'll add (this is mostly my opinion), this is a game that you play half for the plot (the girl's routes are interesting and distinct, and the true path is a doozy) but also half for the experience. The various hijinks along the way, trying to not hit cats with your baseball batting (unless it's the fat one), fighting your friends using random weapons thrown by the bystanders (and getting to give them terrible nicknames if you win), helping someone sneak into the classroom by throwing them two floors up (complete with a minigame).. It just all adds up to something extremely unique and unlike any other VN I've ever seen.
Honestly, I'd say give it an hour. You'll know if the general flow and humor of the main part is enjoyable to you and if so, you can stay for the rest. Do note though that basically all routes get quite serious once you split off the main path (both girl's routes and the true ending), so it's not just fun hijinks. It's a perfect mix of both I'd say.
Also for sure play the steam version. It not only has all the content from both the base game and ecstasy (minus the H-scenes, but honestly they completely don't fit this game and it was only one per route anyway), it's a complete engine rewrite that runs and looks much better.