This is a good book in the right hands. If you are looking for the definative book on mushrooms, it hasn't been published. The closest equivalent to definative is the David Arora Mushrooms Demystified. This book by Miller is a FIELD GUIDE (and maybe 1/5 the size and weight of Demystified), it is very, very short on the number of species covered ('only' hundreds out of thousands). Do not use this book to decide if you have harvested an edible mushroom. There are a great many edible mushrooms that look like a great many inedible and poisonious mushrooms and YOU CANNOT DO IDENTIFICATION BY COMPARING PICTURES.
Understand I am not in any way dissing this book; Miller knew his stuff, and this is an excellent guide. I bought a copy when it was first available, and it has already seen several days in the field. I learned about it from a well respected expert who had also purchased a copy. But I also already had a well used copy of Arora, and I have been foraging for many years, and I have gotten instruction from people like Larry Evens, Gary Lincoff and David Arora, and I STILL MAKE MISTAKES. The critical feature of a field guide is the Key that walks you through the identification process. This book (Miller) has a somewhat simplier key, that I can run through quickly (and larger type which is nice for old eyes in the middle of the forest). I would never eat off the identification from this book or any other. I have already found semi-common specimens where I know the species, that Miller doesn't cover. It's a nice addition to a library that also includes something specific for your region, plus Arora's Demystified. I would take the time to put a plastic cover on it, and it is a good bit heavier than the Audubon guide. However, if it comes to it, I will be carrying this guide in my backpack rather than any of the others I own (and I own a bunch of mushroom books).