I bought this before I did my first Triathlon and it really became my bible. It has everything that you could need in it to feel prepared, from diet tips, to equipment, to training programmes and also how to cope on the day. It helped me to feel really prepared for every eventuality and it meant that not only did I get a great time, but I also loved the event, and as a result I am planning on doing 2 triathlons this season.
Equally, it doesn't then become useless once you've done a triathlon. The training programmes are varied, from the absolute beginner, to the semi-professional athlete and I am planning to follow the training programme again this year.
Highly recommended book - I looked at some other books as well, but this was by far the best. As long as you can deal with Eric's over-enthusiastic and slightly idealised way of writing (i.e. annoying!) then you'll love this book as much as I did.