There is no doubt that this professor is smart. But there is also no doubt that she is biased and grades according to who she likes and dislikes. A couple of weeks into the class, it becomes obvious who makes her list and who doesn't - and if you don't, beware. She will pick on you for everything - be it because you're 1 minute late once (while ironically enough, she is late herself most of the time), be it because you didn't do the reading (irrespective of the fact that she didn't list it in her every changing, never up-to-date syllabus) or be it because your essay is too long, too short, too wordy, or simply "a sequence of true enough statements." But if you're her favorite, you're good. You can be late, miss at least 30% of class, do about 50% of the homework and barely participate and still do just fine.
I do not doubt her intelligence, but I have never had a professor that was unorganized, subjective and unprofessional to such an extent. If she does not like you, she will be mean on a personal level. She is also an avid advocate of fighting grade inflation, so don't expect an easy class. I obviously wasn't one of her favorites and getting an A- out of the class was no easy task: I did all the homework, attended and participated in every class, and was always among the first to post on courseworks.
The class definitely is intellectually stimulating, the readings are for the most part interesting, and class discussions were abundant. Just hope that she decides to like you.