If you could have only one book on Buddhadharma...
If you could have only one book on Buddhadharma, this is the one.
Whether you're a seasoned 'old salt' or a 'total beginner', I don't think you could find a sharper sword to cut down subject and object, or one that is more gently (or more firmly) applied.
Anything by (or about) Shunryu Suzuki is worth a read, but this is the first... and it's an absolute gem.
A book for those interested in the practice as opposed to the theory of the Dharma.