The subject of bioinformatics is huge and is continually evolving and expanding. What this book does is try to pull together several concepts in a light easily readable context. I've been looking through it for a few weeks now and it is by no means a book that will introduce you to the concept of bioinformatics, it seems to be more of a book that will be useful to those working in the field for a while that need to catch up with recent developments in the wider scope of things.
It would seem to me, as someone relatively new to bioinformatics, that most bioinformaticians work within a very specialized area, this book would do a good job in widening the scope of knowledge of these people. It may also be a good book to help final year students pull together concepts learned on their courses. As with other "Instant Notes" series books, the chapter summaries are absolutely fantastic - and the links to related chapters and linking concepts are as good as you are going to get without using HTML. Overall I would say its a book worth having if you work in the field...but keep your senses alert because things are happening so fast!