You think Mo'Nique is bad?!
I don't think she is "brilliant". I thought her performance was incredibly one note and her "big" scene felt incredibly forced. It's fine for what it is, but nothing special.
It was forced. Her character was forcing herself to justify her actions and to appear as if she's a good person, but she fails terribly. I found that to be pretty complex. Otherwise, she may appear one note (possibly) but her performance also feels pretty realistic. I think people connect to performances that feel honest in their lives. I've known people like Mary through my friends. It's one of those performances that feels simultaneously like a horror film monster and a severely abused, incredibly weak woman.
Kendrick in Up in the Air feels one note. I feel that her big scene where her boyfriend breaks up with her was supposed to make the audience tear up and feel bad. Alternatively, my entire broke out in laughter. I laughed too - not because I was joining in - but because her breakdown felt forced and dishonest. I wasn't connected to her character at all. I guess she's kind of cute though.
Maybe forced was the wrong word, or at least forced in a different manner than what you are speaking. I get that her character was putting on that front of caring for that scene. I think I mean forced in that Mo'Nique was trying so hard in this film to prove that she can act that it really rubbed me the wrong way.
I do not think that scene was about making the audience feel bad. It was about a character who had been, up until that point, someone who thinks they know all they need to know about the world and as emotionless as she possibly could be just losing it, in a totally embarrassing way. I think its an extremely funny/charming scene and felt honest to me, anyways.