This is a very good guide to the basics of GIMP. However, it is important to note that this book is severely outdated. GIMP, being part of the GNU, is constantly changing, and many times I found myself struggling to find a button or executable action that was either moved, replaced, or removed in newer versions of the GIMP.
David Bush's style is also quite wordy and may be difficult to follow for many readers. In short, if you are interested in learning the GIMP, I would suggest getting another book unless you are planning to struggle with this book.
GIMP is a great program and I use it instead of Adobe becuase, well, it's free! I highly recommend anyone dissatisfied with Adobe's performance to get a good book along with the GIMP. You will not be disappointed with the GIMP. However, please look for another book becuase this book will not help you unless you are running a very old version of the GIMP.