Buddha's words should not be divorced from the time in which they were spoken and the author has made that clear in this compilation. For the practising Buddhist, the preface (if not the whole book) is worth reading, as it deals, I think correctly, with the problem of "atman." Atman is not "soul" or conventional selfhood, it is rather a mysterious ego-entity moving from one body to another in the proposed Indian theory of reincarnation.
For the practising Buddhist of today, the book is no longer that useful as there are now modern translations of Pali Canon, which suit better to our modern way of thinking. For the hobbyist researcher into Buddhism, there are two resources I've seen on the Internet that may be useful:
1.
http://www.tipitaka.org/
2.
http://dsal.uchicago.edu/dictionaries/pali/