This interesting and indeed, informative work, was first published in England in 1989. Some of the material, particularly that addressing optics and such, will be a bit dated but most of the other information is as current today as it was when the book was first published.
Basically this book is targeted for the beginning or mid level birder. This IS NOT a field identification guide. No, what it does cover, and at some depth, are the basics of bird watching. It covers the equipment available and necessary, bird habitat, i.e. where to find bird, basic bird behavior, anatomy, habitat, migration patterns, nesting habits...well, just about every aspect of the hobby of birding/bird watching.
One of the strongest points in this book are the wonderful photographs; not only of birds of bird habitat from around the world. Photography is top of the line.