I think the pricing information presented is relatively accurate and realistic FOR THE INSTRUMENTS THAT ARE INCLUDED. If anything, the error is on the conservative side - i.e. many instruments SEEM to be priced lower than actual current going prices. Good if you are buying - not so good if you are selling.
I have 4 complaints with the book:
1)The ONLY pricing information presented is for instruments in excellent condition. The authors provide a sentence or two as guidelines for valuing guitars in less than exc. condition - but these are vague;
2) There are a number of inaccuracies regarding years of manufacture, model numbers etc. One example: I own a Hofner Senator which I have dated to 1954/55. However the guide appears to think this model was first produced in 1958. vintagehofneruk.com clearly shows this to be incorrect;
3) I guess they define "vintage" differently than I do. While omitting many true vintage (pre-1980??) guitars they waste space with Indonesian garbage like the "Hamer" Slammer - "made from 1998 until the present". How on earth is that VINTAGE??
4) Most significantly is the VAST omission of instruments that clearly should be there - at least in my opinion. I own 11 vintage guitars. Five of these are not mentioned in the Guide at all. I have tried to price other instruments I was interested in purchasing and in the majority of instances I could find no information in this book. And I don't think I'm picking off the wall weird instruments. Some of these have been Kay, Harmony, Norman, Regal, Voisonet, etc. all of which should have made it into the guide in favor of Slammer.
If you are looking for encyclopedic coverage of priding for vintage guitars you won't find it here. I won't buy this same guide again.