They have a card system for getting chores done, which probably would work for a lot of people. I now use and prefer to-do lists, but the card method is flexible. I used to use a similar system with sticky notes (less durable than cards) before I read this book, and they proved that for them and many others, it works.
As with a couple of other organizing books I've read, my main critique is that they don't allow sufficient time to do things. They apparently were stay-at-home moms who are not under the often stringent time constraints many others must deal with. If a job didn't get done one day, it could get done another. But the estimates for any task at any time, in my opinion, simply are too low. Can you clean a floor in 10 minutes? People are different, and have different sizes of homes and so forth, but I don't think I could do most chores (which also include errands to stores and so on) as fast as they can. Can you do a week's worth of grocery shopping, start to finish, in 45 minutes? Car to store to purchases to standing in line to loading to drive home to unload and put away?
If one takes the time estimates with grains of salt, the rest of the book is helpful, and since most readers won't be starting from the extreme situation that these sisters did, they won't have to exert themselves as much to dig out. Certainly worth a try.
Personally I enjoy reading about other woman's personal lives and I enjoy humor, however if you are actually looking for a book on organizing you are much better off with the original SHE (Sidetracked Home Executives) book that they wrote.