Roger Tory Peterson never was going to paint images of the underside of warbler tails from six different points of view.
That in essence describes the detail and value to be found in a very useful and well-done new birding field guide: “The Warbler Guide” by Tom Stephenson and Scott Whittle. Published by Princeton Press, the book contains hundreds (thousands?) of photographs of warblers from many points of view, including directly beneath the bird (a more common viewpoint than you might think). And much more.
Warblers are notorious for giving the observer fleeting and partial views. Field guides on the shelf today, regardless of the number of images offered, ultimately give you one option: extrapolate species from the fragments of information available.
Stephenson and Whittle, using photos taken by dozens of photographers, offer you much better ID odds. They accompany the photos with clearly written descriptive text that focuses point-by-point on the major identification marks. Photos of and text describing similar species offer comparison assistance should confusion arise.
Vocalizations are treated in great detail. Sonograms present visual representation of what you hear.
The book has range maps and migration charts showing usual wave patterns (early, middle, late). These are good range maps, colors strong and very visible, one from the other. (Some books go unnecessarily subtle.)
The market for identification guides has grown almost exponentially in the past two decades. That seems to have spawned a drive for differentiation, one book from another, that has worked to the benefit of us all. This book is a fine example of that. It certainly expands the information available in any single books on warbler ID.