This book outlines the ways in which Sinclair Basic can be used to exploit the capabilities of the ZX Spectrum in just 76 pages. The user manuals take 262 pages.
Manuals are usually a neglected component in the typical micro package. In this case, however, the publication of an alternative guide cannot be interpreted as an indictment of the manufacturer's own offering.
Its author, Robin Bradbeer, co-wrote the introductory booklet and edited the programming manual for Sinclair.
If you have a Spectrum, find the documentation reasonably useful and want to move on to bigger and better things, this is not the book for you. But if you find the manual difficult to understand, the same information couched in different terms may shed a little light.
This book would certainly serve as good pre-investment reading for prospective Spectrum owners.