So obviously the author doesn't have four and counting kids, homeschool, or live on a single income in one of the highest COL towns in the US. So much eye rolling went on during this read. A lot of things in my home don't give me joy, but the kids have to learn math, I can't afford to not buy my toilet paper in bulk, and when your preschooler wants to learn how to make paper snowflakes, it would be selfish to say no just because you hate little pieces of paper. Baby gear--carseats, cribs, etc - - take up a lot of space, but it would be irresponsible to get rid of things between babies. Some of KonMari's statements are hilarious - - if you properly tidy your home, you will never have to do it again? I am currently sitting in our library/den, surrounded by a doll campsite that I let my girls set up because I believe in imaginative pretend play. Nothing is in its designated place because they're playing with it! Um, pretty sure our daily tidying routine before bed is inevitable. And the ideal home she describes sounds sterile and unwelcoming to me. I prefer a clean, tidy home with designated places for everything but still at least a bookshelf in every room and the stairs. My thousands of books spark joy in me as well as my husband and kids. No one is going to convince me to get rid of them. 
 With that all said, my grandma was a borderline hoarder, my dad inherited her junk and her tendencies, and I don't look forward to having to deal with all that junk one day. I wish my parents were more willing to get rid of things that they are only keeping out of a sense of obligation to someone who passed away ten years ago. They could benefit from more of a KonMari mindset. 
 It is easy to laugh at the joy test, but used with common sense, it can be helpful. There was a line about clothes and how women tend to keep things that they don't really love, just because someone gave it to them. I am pretty brutal about culling my wardrobe, but I definitely am susceptible to hanging on to free clothes just because I can't afford to go out and buy new ones that "spark joy" whenever I want. Reading this encouraged me to think about my emotional response to my clothes and got a few more things out of the closet. And toys can so easily get out of control, so it really is helpful to go through bins and handle each thing, getting rid of stuff the kids simply don't play with or need. 
 I also think she's right that organization is not the same as decluttering. My dad is always wanting to build us more storage, and we don't want it because we would just fill it with stuff. Better to be limited in space and forced to get rid of stuff that doesn't fit than to beautifully organize junk we don't need. 
 All in all, not super helpful to me, but could be moderately useful to a different audience.