I recently reread this after many years and it's been interesting to note my reaction.
While I was definitely inspired by the lofty ideals and sweeping language of this book on my first reading, my much-older self is forced to note the many, many holes in Thoreau's premises and arguments. His passion can't be denied, but his prose reads exactly like the "minimalists" of the present day, who pare their belongings down to 50 things, or 100 things, or 15 things, or whatever the current fad is.
The thing that rubs me the wrong way about Thoreau and the minimalists is their insistence that their chosen life is the only one worth living, and that all other ways of living are suspect, wasteful, or otherwise undesirable.
Yes, I'll read it again for its exploration of the beauty of nature and the value of finding inspiration in your own backyard, but I lost some idealism along the way, and perhaps one needs idealism to fully appreciate Thoreau.