This book is a compilation of chapters by a variety of authors who are all experts in the business analysis domain. Thankfully though, the editors have a good job of keeping the structure, language and depth pretty consistent. It is consistently fairly dry but there was little that really sent me to sleep like some books in this domain that I could mention. I think it covers the breadth of skills you are likely to need as a business analysis, but keep in mind that it is published by the British Computer Society to address the ISEB Business Analsys Diploma, so it may cover more that most analysis will use in their daily jobs. In terms of depth, it gives you enough to get started and hold your own for a while, but you will probably want to invest in more detailed references on specific topics such as Soft Systems Methodology, process modelling with UML or data modelling with ERDs - depending on your previous experience and the demands of your role.

In summary: a highly recommended introduction to Business Analysis, useful whether you are new to the role, thinking about a change or have some experience and want to work out in what direction to expand your knowledge.