What could possibly be new here?
If your curious about Henry David Thoreau, you can go almost anywhere for information, starting with the very deep websites of the Thoreau Society or the Thoreau Institute of the Walden Woods Project. If you’re really serious, you can peruse all 36 chapters of the bicentennial volume Thoreau in Context, edited by James Finley, or read Laura Dassow Walls’ excellent doorstopper of a biography, Henry D. Thoreau: A Life.
If you’re curious about the beauty of Walden Pond as a place, there are dozens of photo books available, many on private coffee tables and on public library shelves. My favorite is Scot Miller’s illustrated Walden.
If you’re interested in the human history of the pond as a single place, there is a good one by W. Barksdale Maynard — Walden Pond: A History.
But if you want to know about the actual place in some detail, the whole place, then the only book I can think of is The Guide. In it you’ll find an easily digestible explanation of how this kettle lake came to be, a tour of the pond’s many quirky and special places, and a color-coded survey of the people, critters, plants, and sounds that Thoreau wrote about.