Park is a really good professor. I had him for two quarters and I'd definitely recommend you take him. His class is pretty straightforward, as long as you study the practice midterms. If you don't do well, he's very helpful in office hours too. He definitely wants his students to do well, and he'll do a lot to make sure you get the grade you deserve.
Park is an excellent professor and probably the best one I have had in my two years here. His class is very organized and the lectures are very clear. And he is not your typical professor. He is a younger guy in his late 20's and keeps you entertained with jokes rather than boring you to death during lecture. Towards the second half of the quarter i went to his office hours every week and he is very helpful. Though he is very busy with research, he is always quick to communicate through email and schedule office hour appointments if needed. If you are going to take 32A or any math class i would take it with him. I got an A in his class and the previous quarter i got a C+ in 31B with a different professor. Just beware that all the smart kids take Park because he is a great lecturer.
Probably the best math professor there is at UCLA, his teaching style is reminiscent of high school teachers - spoon-feeding, which is great because you will understand everything if you go to class. Even if you don't get the stuff there, just copy down the extremely-comprehensive notes anyway and read it over again when you get back and you'll understand it perfectly. College would be a breeze if everyone taught like him.