I personally hate 'chosen one' characters in stories.That's because it's done so often, and is usually a lazy way to explain why the protagonist is important when they're usually some teenager who knows absolutely nothing and has no skills. But, it also seems to cling to the 'chosen one' cliché with Eren, and that is regrettable. It felt like they were doing what Game of Thrones does, focusing on the big historical picture, rather than the narratives of specific characters. Ymir's story resonated emotionally with me, and I felt that it was well done, almost to the point where the main heroes of the first season seemed like interlopers. Weakness and lack of character development in Mikasa and Eren are more than made up for in the deep character exploration given to other characters, most strikingly Ymir.
I kept watching it and kept wanting more. But, what I got was entertaining, exciting, dramatic, and tear-jerking enough. The length of 12 episodes was a bit of a let-down, considering how strongly I was anticipating more Attack on Titan.