Its an excellent book, extremely comprehensive in all respects, dealing with clothing, foods, communications, stores, routeplanning/navigation etc. It falls down in two areas - though Tom Sheppard has travelled by motorbike in the Sahara a lot, he doesnt mention it as a means of transport in any great depth (its already a huge book and I guess he feels that bikes as self-supporting long range machines are limited). It also skips over medical care in the field, but K Melville's "Stay ALive in the Desert" is best for this anyway.
In terms of expedition planning books, it is the best in the field. It has big chunks of the author's 'Desert Expeditions' booklet that he wrote for the RGS some years ago, but thoroughly updated.
Hard to get hold of though - seen a few copies on Ebay, nothing recently.
'91 LR 110 Def/Disco hybrid "Elsa"
Bring me the horizon....