Kristen's class is a little bit of a conundrum. He's a fairly dynamic lecturer, and explains concepts pretty well, but his workload is absolutely impossible. After sitting in class, you can be sure you know what's going on, but then taking a glance at the homework makes you think you picked up the problem set for the wrong class. He asks very tedious, multi-step derivation-oriented problems, and is an extremely harsh grader, so don't expect much partial credit. Be prepared to punch long strings of numbers into your calculator in a minimal amount of time on exams, and if you hit the wrong button in one of the steps, be prepared to lose most or all of the credit for the problem. All in all, a very unsatisfying course- the class was okay, but you really felt like he was out to get you with the difficulty of the exams and the grading. Do yourself a favor, and wait until Frits or someone else teaches this course.