I'm glad you found it easy. Personally, I found it very challenging: although I thought I matched the requirements for mathematical background that Prof Roughgarden outlined in the intro lecture, it turned out to be a struggle to keep up with some of the concepts when it came to apply them in the theory questions.

The programming exercises were fun, but I don't think they were really the point of the course - this "part 1", at least, was much more about analysis than about design.

As a contrast, I've just started their compilers course: there the theory questions are slightly easier, whereas the programming questions are much more involved - the first one has already taken me several hours and I'm nowhere near finished.