It is finally done. I have been reading this manga since the summer of 2017 and it is the first manga I've ever read so it has a very special place in my heart. This probably won't be an objective review but I'll try my best.
Story: The thing I used to like about AOT's story is that it was always unpredictable to me. When I was reading it, I was always like 'What the hell, why is it like that?' and I personally really enjoy these kind of things. Everything was great, till the end. I was wishing for an unpredictable end but when I read the chapter 139, oh man. Everyone was theorizing about it and the fun part of making theories is to see what percent of your theory is true or not but it was just like theories. Neither less nor more. It was a disappointing end. I truly hate the characters who does lots of unacceptable things but in the end everyone sees xir as a hero, like Itachi in Naruto. Eren killed about %80 of humanity, okay, but oh no it was for the sake of Paradis and his loved ones and than this fact justifies everything he did. I really thought this manga'll be a masterpiece but now I'm laughing how stupid I was.
Art: From 2009 to 2021, the art is improved and it looks beautiful to me. But I saw mangas with much better art.
Characters: The thing I like about characters in AOT was there is no completely white or completely black characters. They are gray, some is much lighter, some is much darker but there is no bad one and good one. Again, in the end, I thought Eren'll be a really dark gray character and we'll learn his true goal and it'll be really surprising but than chapter 139 comes and says 'No, it was all, he killed %80 of humanity just because of Paradis and his loved ones.' Don't get me wrong, I'm not complaining about that he killed lots of people but I'm complaining about that the only reason he did was to protect his island. It'd have better, but Isayama decided to end this great manga with an average ending.
Overall: The story started very well, developed very well, reached at its peak very well and ended really bad. I expected more interesting ending but this is what we got. Wasn't the worst story, but really far from the best.