If you want a good college experience, definitely take Williams. He has all the elements of a good professor - Highly effective, concerned about student learning, and something hard to find at UCLA: fair grading. Get ready for some down to earth, bottom-line learning. He teaches the way it's supposed to be taught.
There were no surprises in the class (i.e. The average grade is somewhere between a B- and a B, and he asks questions on exams that relate to the things he taught in class albeit in a tricky form). He is the fairest grader I have ever seen. He gives partial credit for just the correct setup of these problems, and even if you don't, he still gives some credit if you illustrate what concept to use. You end up with the grade you deserve. If you need help, definitely go to his office hours. It seems impossible to make him lose his composure based on my experience.
I have nothing but respect for Professor Williams.

Prof. Williams is a nice guy, he knows his material and he knows how to teach. The material isnt that hard if you had previous experience. But the fact that the class is bell-curved will bring on somewhat more pressure. I would recommend him though.

Prof. Williams is a really nice guy and a good professor. While his class was a challenge, I definately learned a lot about physics.