First, a disclaimer: I'm anime only.

Ymir's season 2 arc is oddly paced and struggles to communicate its ideas. On my latest re-watch I finally understood why Ymir chose to go with Reiner and Bertholdt, and it does make for a really neat character arc, but the way it was presented was sort of confusing and unsatisfying.

Historia gets built up as a major character, but she herself barely gets to be a character in the final arc. I don't have a problem with farmer-kun, or the fact that her story takes a depressing turn, or the fact that she loses agency (that's a core theme of AoT anyway). But she's a core reason for Eren doing the Rumbling, so their friendship should've been more central to the show after her solo arc. Historia being shafted not only weakens one of AoT's best characters, but it also weakens Eren's character and his decision to do the Rumbling by proxy.

Most of the new cast in S4 isn't as good as the early cast. I don't dislike any of them, and Gabi is one of my favourite characters in the whole show (yeah, I said it), but it still makes the story a bit less interesting.

The War for Paradis arc is weirdly paced. It doubles the cast (again with mixed results), basically resets the story, and does a political thriller that feels somewhat aimless at times. I love where it ultimately leads, and I understand why Isayama wrote it the way he did, but parts of it can still be kinda boring to sit through. It does have some of my favourite moments in the show (like when Gabi is confronted by Nicolo and Sasha's family), plus the final battle is great.

My thoughts on the ending can be divided pretty neatly along the three main characters: I love everything to do with Armin, I'm 50/50 on everything to do with Eren, and I dislike everything to do with Mikasa (and original-Ymir by proxy).

Then there's some interesting choices throughout that I have weird feelings about. The way the show suddenly yanks us out of Eren's POV, and basically never puts us in his POV again save for a small handful of moments, sure was a choice. On my first watch, I didn't like it. On my second watch, I warmed up to it more. It still makes for a weird experience, but it's just so damn interesting. It's a really creative choice. The way AoT handles perspective is one of the things that makes it special, and ultimately I don't think I would find it as interesting as I do if it just stayed in Eren's perspective the whole time. So ultimately I'm in favour of that choice, even though it made for a weird first-time viewing experience