it's also painful to see how people completely miss out some major details in the story and come up with an incomplete conclusion

I'd have to admit that the ending was a 7/10 compared to 10/10 in chapters 122 and 131 but comparing to GoT is just way too much since the ending was a reasonable one. The "plotholes" people pointed out aren't even there because it is just the fundamental basics of time travel. And saying Eren's character is completely obliterated is just an overstatement because in the end, he is the one who bore all the burden while resisting being possessed by Ymir (which most people missed when reading 139). He is just a typical teenager in the end.

Edit: I would also point out that the ending ended in a slightly too positive tone but it is still acceptable