i agree with you OP that c4 was easy- c3 was harder imo, didnt know what all the fuss was about with c4, people were like "omg this is ******* impossible!", always found differentiation & integration dead easy too, though i also found differential equations easy, the only parts i didnt like so much about c3/4 were proof & some trig questions can be tiresome
wish i did further maths instead of biology... >:|