Heather It really does make more sense if you read the first three books - at least the previous two, since Vol2 introduces Will (who is a protagonist in this book) and Vol3 leads into into this one (the thing Will "loses" at the beginning of this book is something that he learned in Vol3.
Orinoco Womble (tidy bag and all) You really need Vol2, at least, where Will Stanton is introduced as the sign-seeker. I find the "Drew family" stories unnecessary and not as well-written.
Katie I just read it as a stand alone and I kept thinking I was missing something, i.e. I was convinced that I should have read the first 3 books...
Steven Jameson They had us read this over summer vacation when I was in elementary school, I didn't realize until now that it's part of a series. I thought something was off but it wasn't enough for me to question it I guess.