It's not much about maths, it's a memoir by a particular mathematician written at an unhappy point in his life, reflecting back on what he has done. It belongs more to the literature about artists and creativity, than to books of mathematical content. For that, see instead Hardy's Course of Pure Mathematics [1]
If you do read the Apology, be sure to get an edition with C.P. Snow's forward, which gives the back story that puts Hardy's memoir in context. It also includes the wonderful story of Hardy and Ramanujan.
If you do read the Apology, be sure to get an edition with C.P. Snow's forward, which gives the back story that puts Hardy's memoir in context. It also includes the wonderful story of Hardy and Ramanujan.
[1] https://en.wikipedia.org/wiki/A_Course_of_Pure_Mathematics