Any book like this is going to be difficult. This particular book is intended for the absolutely novice to ITIL or ITSM in general. For those not used to using metrics, it presents a useful overview of what to collect, and what value that information may be (and all kudos to the author, they include things beyond the normal Incident, Change, Problem Management that appears to occupy 80% of similar texts).
For those who have used metrics to manage business units before, it is probably a little light to be useful.
My view if you are new to ITSM and trying to pick it up in a hurry, this might be useful. You can read the 150 odd pages in less than and a couple of hours (and there is quite a bit of repetition) so it is not a huge investment in time.
If you have much of a background in IT / IS Management, there probably isn't really much to keep you enthralled here. Still, I expect it will be a useful thing to have in the library so I can pass it around no IT business colleagues to get them thinking.