https://www.gutenberg.org/files/38769/38769-pdf.pdf

The way calculus was taught changed after Hardy’s A Course of Pure Mathematics came out. People in general like how direct this book it is. It is easy to understand things like what limsup and liminf mean from this book. The problems look at Leibniz’s rule for finding the derivative of defined integrals. However some parts are out of date. Hardy doesn’t use Riemann or Darboux sums to explain integration; instead, he uses anti-derivatives. More recent calculus books like Michael Spivak’s Calculus, are probably better for that.

The Hardy’s book is good for people who like clear and logical writing. It had an effect on people like Alan Turing. People who like a simple style will like it. It changed the way math was taught, but it’s not the best choice for a current textbook.