It is very easy to give a description of this book. It is a must, if you want to work with SQL Server as an administrator. Of course there are things that are not really necessary to know, but in general the book describes quite well, some of the mainissues when it comes to performanceproblems in a SQL Server: Memory and Locks.
Besides that there is a good deal of information about the storage engine and how it works, and we also look at the CPU.
On the downside, I think the book uses to much time talking about other approaches like SQL Nexus, and therefore it places it self between a good technical book and a book for administrators that does not want to be to technical.
It can be bought at amazon.com