If you're looking for a book that explains operating systems from start to finish then you've found it here.
If you're looking for a book that goes into detail on everything operating systems (without making you fall asleep) you've found it.
All in all I would say this is a brilliant book for beginners and intermediates. It covers all the necessary ground work to get beginners off to a flying start but is clearly sectioned so that people studying or interested in more detail can find the information they need without having to read a lot of boring introductory stuff.