Did WIT studio ruin Mikasa's character?

I haven't read the manga, watched the anime only. I have seen some videos on Youtube, claiming a lot of important dialoges in the manga were cut off in the anime, causing people to have an overwhelming experience with Mikasa's character development. So my question is towards you, manga readers, do you agree with this? Do you think WIT studio made a bad job with some characters?

(Also unrelated to the question but can someone tell me how many mangas there are in total? I want to start reading it. I'll buy them because I really enjoy holding a book in my hand.)