The fact you were annoyed by her character shows she was doing a great job acting, as did everyone on that show. That she gets slowly sucked into the ever growing criminal activity, as does Walt, is what makes the show a very good drama. Still one of *the* best show endings.
Actually, this is not true at all. Both the actress that played her, and the shows creator both have stated and written articles that the backlash and dislike that the character has received was unintentional and that neither of them fully understood it. Therefore it was not good acting at all.
I was trying to think of anyone in that show, family or friend, who was not brought down by Walters criminal enterprise. I was thinking there was no one who escaped but then I thought of someone very close to Walt who was not sucked in and brought down by his meth making.
Can you think of who I am talking about? Certainly this person was very adversely affected, but they were never active and involved along with Walter.