David Allen Sibley's new book, "The Sibley Guide to Birds," second edition, is a fine book. I like it. I have one. I use it.
Why? I like Sibley's artwork, first of all. I do find the text helpful. I even like the range maps (more on that in a moment).
Artwork: Birding is a visual game, to state the obvious. I believe that most people choose a field guide based on their reaction to the illustrations. You either like the art/photos or you don't. I don't believe that attraction to text or anything else overrides reaction to the art.
My first field guide was the Peterson, eastern version. Of course, when I bought it there were but two real choices, Peterson and the "Audubon Land Bird Guide: Birds of Eastern & Central North America From Southern Texas to Central Greenland" text by Richard Pough, illustrations by Don Eckelberry, the title alone worth the purchase. Eckelberry drew his birds with more flare than Peterson. Eckelberry's birds were shown in realistic poses; they had movement.
Peterson's art won the day, however. As a beginner, I loved the little arrows that pointed to the critical field marks on his perfect profiles.
I never went to a bookstore to buy a field guide, and made a choice based on text. No. It's how you feel when you open the book and look at the pictures.
Over the years I've acquired about three dozen other field guides, some general for North America, some east only, some west, and others for warblers, raptors, shorebirds, and seabirds.
I have these because I thought I would find them useful. In most cases they have been, if only now and then. The book in the bird box in the van, though, and the one on my desk, those are Sibley's. Because I like his artwork.