I loved this book, and how it is written. I have strong mathematical background, so the initial chapters were rather unnecessary, although I read them and I really enjoyed re-learning some mathematical details with some intuition I had lost. Then, the machine learning examples, including regression and Bayesian perspectives, is really good and complete, and it is really helpful to have a strong basis on the mathematics behind most popular models. Usually people that use these models don't stop to think on these details, but once you get them, you have a better perspective of what the models are doing. Also, pictures and examples are very nice.
In summary, it is a good book, gives strong mathematical and Bayesian perspective, good basis to explain how models work to others, but the initial chapters are too hard for someone without mathematical background, and at the same time, they are sometimes dull for someone that already knows them. Specially because it hops from very basic stuff in linear algebra, to complex optimization results. They are definitely not for someone that do not know them previously.