I genuinely believe that her character arc was well executed. I rewatched a lot of the old seasons and she was always meant to turn into a Mad Queen when the moment comes. Yes, they rushed the last 2 seasons and yes, they ruined pretty much every other character, but not hers in my opinion.

The misconception about her comes probaby because she was introduced as a victim and a "good" character, that everyone should cheer for(same as the Starks). She is also cool because she has dragons and acts cool by liberating some people. Another thing is that people always knew that she will eventually come to Westeros to fight for the throne, so nobody was afraid of her dying somehow in Essos. And yep - it was a well executed twist on a higher level