Aw, dorktastic! I can totally imagine some nerdy little kids of yesteryear poring intently over this tome, memorizing its factual information and dreaming of visiting these marvellous dams, bridges, and geographic features. Halliburton's voice is perfect for the book: he's just so excited about even the driest data! This delight in factual information is especially impressive in an individual so outdoorsy and adventurous, as these qualities are not often found together.
This book made a generation of children dream of travel and adventure. I can't imagine it holding much interest for the youngsters of today, however. What attraction could these figures and grainy black and white photos* hold in the era of wikipedia and (in color!) travel documentaries?
*Halliburton was actually a pretty good photographer; the cheap reproductions in this book don't do his work justice. I couldn't find alternate versions of the ones from the book, but here's a photo of his "Hangover House" in Laguna, designed by his friend William Alexander (Alexander's partner Paul Mooney was Halliburton's editor).