Interesting book this. It is a good buy if you're thinking about certification. That is exactly my position at the moment and I am currently reading 'Solaris 8 System Administration' in the Exam Cram series published by Coriolis. (Strangely Martinez does not mention the Exam Cram Series at all, indeed the Unix side of certification is seemingly not covered to the same extent as the Microsoft and networking, etc.)
My objective in approaching certification was just for fun, but this is certainly not Martinez's. Her emphasis is on the job and career benefits - how to make it pay. The benefits of certification are not as obvious as they might seem. On the one hand I see some job advertisements stipulating certification. On the other hand gurus on the news groups I read seem quite scathing of their benefit. So, I suppose it depends who's sitting across the table at the job interview!
Most people will only be interested in two or three certification attainments at most, say CCNA and MCSE. The current tome covers nearly everything that is out there. From 3COM's discontinued MNS to Alcatel's Certified Switch Specialist, ACSS are covered in 260 pages. Hence someone interested only in CCNA will have a lot of wasted book space, but that is unavoidable in an encyclopaedia like this.
The first 321 pages are concerned with really meaty stuff; preparing for the exam, career planning, study methods, tax write-offs (for the self employed - US legislation, but the gist is the same), persuading employers to help with study costs, dos and don'ts.
I found some of the links to certification programs were out of date, but this is a small criticism and the hits were near enough. A good buy, especially for libraries and career officers.Wireless, Signal Processing etc.