A bit biased since I did my master's thesis at Center for Biological Sequence Analysis, the lab headed by one of the authors. That said, this is a fantastic book. Focus is on sequence (DNA, RNA, protein) bioinformatics and a must-read if you are active in that field. I would also go so far as to say that it is a great book on bayesian methods and machine learning in general and can be read by someone not active in bioinformatics. Highly recommended.