One of the more difficult classes at UCLA, but WELL worth the time and effort spent. Significant and view altering ideas are introduced. This class will really make you think and re-evaluate the mental framework that you've looked at things at in the past (goodbye bullshit non-descriptive differential equations). You can get a lot out of this class if you're well versed beforehand in some of the stuff they talk about, but it really doesn't matter - this could be your first class at UCLA and you'd still be able to follow along and get a lot out of it.

The weekly assignments can become annoying and some of the lectures can get dry, but overall are much more engaging than other classes (they are almost all in powerpoint, which helps so if you get bored or lost you can go back or skip ahead slides). Anyways, don't be daunted and take this class.
P.S.
The other instructor, Bragin, although he often gets a bad rap, is in reality one of the most caring and dedicated faculty at UCLA. He is serious about the subject material and he is highly demanding of students. I've noticed that the older people taking the class (read those that probably care more about learning for learning's sake) usually get along with him better. If you do the readings and show interest (surprise 20% of the class) you'll get along great.