Maths & Theory, those are the courses for which I did the least, and yet I regard Theory as the most interesting course, it's just that I am very lazy and you aren't required to do any work for the F2 & F3 courses, you have a written exam about F1 & F2, which I didn't take yet, and a oral exam about F3 & F4. But I do know theses courses are interesting, context free grammar, turing machines, complexity, automatons. It's theory but it's theory upon which languages, compilers, algorith and computers a based on.
With Math it's a different, it was fine back in school, because it was easy, dead easy. But university math not school math, it's a lot more and it's complex. And worst for me, but I didn't see any use for most the the things I learned, they did say that some off it is needed for encryption of compression, but we never did any compression or encryption, just abstract theory.
Last thursday we had a Cognitive Science course, and in the course, which btw. is very entertaining, it made click. The lecturer used a picture, taken by a b/w camera, to show when and where you need a formal/mathematical theory. Maths is not just all maths for maths, there is a hidden link between practice and theory.