It's quite well-written but I'm not sure about the actual concept being great. But then I've also never been the sort who needed to freeze a credit card in a block of ice to keep myself from unnecessary spending, which is a similar idea. I guess it's good for someone who really does have a serious issue with self-control, but eventually they need to work on the root cause. You can't rely on a strategy like this forever.
Also, she is still spending heaps! She is basically getting $200/week fun money. After all, she says that "bills, and major expenses, like car, rent and health insurance payments" as well as "must-haves, such as groceries", are not included in this restriction. So she's still spending $867 per month... on what?