This is an encyclopedia, not a textbook. The level of the material presented is extremely uneven, and the book is really not appropriate for an advanced undergraduate course in subatomic physics, as it was originally intended. On the other hand, the coverage is excellent. I could not think of a topic in current particle and nuclear physics that I was unable to find some coverage of here.
Physically, the paperback is extremely massive due to being printed on slick paper. Some very primitive graphing program was used to generate many of the figures in the text, and the strange font chosen makes the lettering look slightly out of focus and not highly legible. There are huge numbers of misprints and even misspelled words. If you intend to read the book seriously, make sure you download the long list of errata available from the publisher's web site.