Kraus knows his stuff. His lectures are pretty simple and easy to understand, and if students don't understand, they won't feel intimidated at all to ask him a question. His tests are really easy (conceptual mostly, but he throws in some calculations depending on the subject) and the homework sometimes takes forever (I think he said something to the effect that torture is the best way to learn Fourier Series). I've had Kraus for 1C and I'm taking him for 131.
Basically, he's ready to answer all questions and he's friendly enough that you won't be scared to ask him. His only weakness is the tendency for his voice to start trailing off. Seriously! He starts off speaking at a normal volume, then his voice starts to fade into a mutter, then after he finishes writing something on the board, his voice will reset to normal volume to start the ride again.

His lectures are pretty good and I loved that he put the notes online for us. He's a lot more clear, organized, and comprehensible than other physics professors at UCLA. The homework was MasteringPhysics. It was difficult and sometimes kind of long, but the real problem was that the homework looked nothing like the tests. In order to do well on the tests, make sure you study the lecture notes and go to the review sessions, because studying the book and the homework problems does not prepare you well. Going to class every day and trying to understand the concepts he lectures on is a lot more helpful than trying to get good grades on the homework, so don't worry about it too much. The midterms and final were pretty difficult, but he's not a hard grader.