I think all of the books I've seen definitely have something to offer, and
all have strengths that differ among the books. My personal favorite for
simple elegance (and for turning me on to these plants) is Schnell's
"Carnivorous Plants of the United States and Canada." It is great for a
beginner and has much to offer an expert, although many will disagree that
pure sphagnum is the best substratum for all CP. I think Adrian Slack's
"Carnivorous Plants" is a classic as well, and there is much of value in
the books by Cheers, Lecouffle, and Pietropaolo. Unfortunately Slack's
book is long out of print (even though it is still listed in "Books in
Print"), and I think Schnell's book might also be. Don't overlook the
classic scientific references by Llloyd (Carnivorous Plants) and Darwin
(Insectivorous Plants) either.
Sean Barry