I was kinda surprised that this was released in September 2011. It seems like it was not updated to include changes in vSphere 5.0 (released for beta in summer of 2011) or even vSphere 4.1 (released in summer of 2010). Specifically, some of the changes to CPU scheduling that have loosened the limitation on single vCPU VMs. Many applications released in the last two years will perform very poorly if placed in a single vCPU VM. Even some roles of Server 2008 struggle with a single core.
The author also goes off on "large single array" SAN configurations. The problem he is discussing (insufficient IOP capabilities) is very real but his blaming it all on single large array configurations is a false conclusion. It's ironic that a "virtualization expert" doesn't see the benefits of storage virtualization, or the waste in traditional array configurations that he seems to prefere. The real issue is people not evaluating their IO needs and purchasing insufficient hardware to meet those needs and growth. More dedicated array configurations have their place in very high IO applications, but to paint "large single array" configurations as a problem is inaccurate and is an argument I usually here from old SAN administrators afraid of losing their jobs.
Overall, this book is mostly a condensed version of the recommendations that VMware makes in their various vSphere documentation manuals and best practice white papers. I could see this book definitely having value to an administrator new to virtualization, but that administrator also needs to do some additional research to get more up to date information.