The Great Pianists - Harold Schonberg

I recommend The Great Pianists by Harold Schonberg.

From Beethoven to Arthur Rubenstein this book covers the history of piano playing and those who have triumphed as truly great pianists. 

Not just a historical book, Schonberg uncovers some of the greatest pianists' and composers' tips and shows some of the greatest troubles they had themselves with the mastery of the piano. As well as this it is one of the greatest guides to stylistic playing, capturing what the composer would have intended with every note and ornamentation. 

This book is fascinating and (perhaps suprisingly to some) a lighthearted read, showing the feuds between great pianists and reflecting on the celebrity status of pianists in previous eras.