This book is suggested, in my opinnion, for those people with a basic understanding of Buddhism. It should be a follow up to introductory texts, which explain some fundamental Buddhist beliefs and the system of thought from whence it comes.
This book is not written simply, and it is especially a text which should be studied in greater detail than say, a novel, becuase here are the rites of one path to awareness.
Ofcourse, some of the ideas are TOO MUCH, and one should be always be aware of the differences between our age and the age in which is was written, for back then times were different, teachers were less scarce, and the teachings far more accepted.
But this is a fundamental book which should be read. Take it with grain of salt, be aware, because it displays methods. And the results of those methods are what we are ultimately concerned with, things that change our perspectives, and in essence, ourselves.