I had him for both 3500 and 4705. He's a super nice professor, and fair with grading. In 3500, the exams were relatively easy, but in 4705 they were kind of hard. However, in 4705, 60% of the grade was HW which helped a lot. The 4705 HW could be conceptually hard, but manageable if you took enough time. Very quick to respond to email.