Hi - I have a copy too and have found it very useful.
If you are approaching Kamailio for the first time it's a good way of understanding the basics and moving towards the additional features the several modules can provide. It is oriented on the routing configuration, so you'll find examples and code snippets.
It can be read chapter by chapter but also kept on the desk for a quick consultation. It's a good ice breaker for people having heard about Kamailio but not having worked directly with it, and willing to get a better idea (first hand experience at the office).
Needless to say, the community is very active and the project evolves quickly, so this can't replace online searches and documentation, in particular targeted to a specific version. I'm afraid I can't compare it with the other book.
Cheers,
Giacomo