I thought Alp was a great teacher. He is very knowledgable, he can communicate really well (unlike most professors in the math dept.) and he is higly organized. On the other hand, his exams and problem sets are REALLY hard, expect to spend lots of time on problem sets and make sure you study for the exams, or you can be sure that you will flunk. On the other hand, because everybody does bad on the exams, the curve makes it up for it. Takes his class only if you want to master the stuff. If you arent interested in calc and only taking it for credit or you want something easy-going and laid-back, take Zhang's class.