I don't think the previous reviewers of this book are entirely fair. I just read it again, and it strikes me as odd that a book that has nice worked out proofs of every major theorem(the proofs are fairly detailed, typical undergraduate level), many relevant examples, and exercises on many levels of difficulty can get an average rating this low.
It has a few typoes but except from that, I think this book is somewhere between high average and good. Three stars would be fair, as would four depending on taste. One or two stars is simply NOT fair.
BUT: You need a fairly high level of mathematical sophistication to apreciate this book! It is about the theory of computer science (ie mathematics) and not a practitioneers handbook although it has many nice algorithms!