I am a little late to the thread. Just wanted to add that this book has actually truly been life-changing for me, as it led me to MMM.
Back in October, I was feeling trapped and burned out at my job. It paid well, but I've never been much of a "stuff" person. We love traveling, and it seemed that was the only time our lives expanded - when we were in nature, seeing new things. We had money (which we mostly spent, aside from some retirement savings), but no time. Kept wondering if this is all there is to life - work, earn money to travel in small gasps, return to your work, retire when old, die?
Read the NY Times article on Marie Kondo's book, and became a person possessed. Went through a flurry of decluttering, getting rid of hundreds of dollars worth of stuff; cut 2/3 of my closet, even managed to trim my personal book collection by 30% (a hitherto-unimaginable feat). Realized could happily get rid of much more if my spouse didn't object. :-) Haven't missed anything we got rid of except some origami paper. Am much much happier for having less stuff in the house - less to stumble over, less to clean, more possessions that truly bring joy.
Hunted for more ideas on decluttering blogs, which led to finding simple living blogs, then the minimalist blogs, then the compact... All the time saying "right on! right on!" and being astonished that yes, there are a lot of people who think like I do, that there is just too much stuff, too much emphasis on stuff, not enough emphasis on time, on living your life. Stumbled upon the Frugalwoods blog and they mentioned MMM, so I clicked over, started reading... the sun came out of the clouds, and the angels sang, and life seemed worth living again :-) Binge-read the posts, upped my 401K as far as it could go, looking into setting up taxable Vanguard accounts for the rest, cutting spending.
So yeah, life-changing...