My review has spoilers so don't read if you don't want spoilers?

I watched the first two seasons a while back and they were okay, nothing special from what I remember. Iroha, Yui and Haruno were probably the only characters I liked, the rest were either forgotten or used as plot devices. I did rewatch the first two seasons to actually remember what was going on, leading up to season 3 and it wasn't impressive but whatever, I liked it.

Season 3 continues directly on from season 2's climactic finale, but doesn't hold the momentum and kind of just goes downhill. It largely revolves around Yukino's ability to decide things for herself but the fact she can't already do what pre-schoolers can is just embarrassing, and the whole execution is lame, especially the co-dependency factor, which makes the ending inherently worse simply because they don't solve their own issues. Instead Yui gives up and third-wheels Hikigaya and Yukino, with Iroha in the background.

Personally I don't find the characters that relatable which shouldn't be surprising considering they're so weird and difficult about everything, especially this season.

Maybe because I was rewatching the show but the convoluted dialogue seemed much worse and almost hard to listen to at times, because istg all Yukino and Hikigaya do is chat shit about why they can't directly help each other and then go in circles, before Hikigaya helps her anyway.

The characters are shallow, one-dimensional cardboard cut-outs that repeat the same phrases, ideas and actions throughout the show. Yeah I get they have their sad pasts, backgrounds, etc. But change indicates growth, and I don't think the main characters actually grow as people. Yui remains mostly the same and the other two only really change their attitudes toward each other, eventually dating in the end. Haruno's clearly complex feelings towards Yukino and the rest of her family are never explored in detail and she's just used to drive the storyline forward.
Not to mention the rest of the side characters are also just plot devices at the end of the day, like Hayama is used as a romantic interest for Iroha and a rival to Hikigaya throughout the show. Except he's pretty much forgotten and unused for majority of the third season, to the point I don't even think they finished the subplot with Iroha and him.

It's a good enough show, these are just my critcisms. I didn't find Hikigaya relatable but I did enjoy watching his self-destructive tendencies cause friction in the club, and Iroha. She literally carries the show and is probably the main reason I continued it but a lack of character depth and development in general, combined with a weak storyline and ending make this easily the weakest season so far. There is also definitely a lack of closure though but I was high so who knows.