Not too easy. Not too difficult.
Lingjiong Zhu is a brilliant man. He gives great insights, is a fair grader, and gives fair tests. Most students think he doesn't teach very well, but I would argue that he just doesn't spend time on algebra and skips steps that are unimportant to understanding the concepts. If you are mathematically acute, you will walk out understanding everything. If you're not, be prepared to teach yourself. Nonetheless, an A will be given to anyone who works for it. He replaces your lowest test grade with the final, and his test reviews are exactly like his tests. Anyone that did poorly simply didn't put in the effort.
This course focused mostly on developing techniques to solve first and second order differential equations and to learn some of their theoretical properties. I also learned to do partial fraction decompositions like a boss from this professor. He has a simple technique/formula for doing them that saves you insane amounts of time. The best parts were learning about the Dirac delta function (look it up!) and laplace transforms.
Hours per week:
Advice for students:
I recommend skimming the chapters being covered before class and actually doing the homework sets rather then looking up the answers. If you do this you will breeze through the course.