What struck me most about this book was the discussion of the political debate at the time. This will sound as more naive than I am, but nothing has changed in terms of how political debate happens.
Towards the end of the book, Egan points out that Pinchot understands how events need to have a narrative, and the side that succeeds in creating the most compelling narrative wins.
My only criticism would be that the end of the book seems a bit disjointed when he tries to tie up lose ends. Otherwise, great book.
(UPDATED 2-24-11) On second thought: I think this book missed some major points of view. Well, maybe not missed them, but I think Egan messed up by focusing too much on Roosevelt and Pinchot and not enough on Ed Pulaski.
In the book, the constant coming back to Roosevelt and Pinchot took away from the history of the fire itself and made it more about their personal history. If Egan had focused more on Pulaski, I think he could have a much more fruitful narrative on the relationship between East Coast and Mountain West. Pulaski seems to embody the well meaning but frustrated attitude towards the East that almost embodies the Moutain West. By making too much of Roosevelt and Pinchot, Egan makes Pulaski seem unreasonable. Even, when in the actual history, he is the most reasonable of all the players.