My overall take on substituting homemade for storebought is this: YES!! Homemade works at least as well as storebought, and is cheap and easy. (But keep storebought tucked in the closet somewhere, you may need it.)
For the individual ideas --
Unpaper towels: Wonderful. They work great. I grab them and use them all the time. You really don't need to have any regular paper towels in the closet except for maybe when you have company who prefers them in the bathroom.
Cloth all-purpose bags: These are great for stashing everything! I am still not using them at the store because 1.) I don't have any in the right size and 2.) I don't have any of any size in the car. I'm working on that. I still use the plastic store bags that I inevitably come home with as trash can liners.
Cloth diapers: They're wonderful. They are somewhat of an expense up front but you can greatly reduce that by making your own out of old clothing and sheets around the house or from yard sales. I do recommend keeping a few disposable ones handy for the diaper bag.
Homemade dish detergent: Works great in the dishwasher and for cleaning everything in the bathroom, just not so much for washing dishes in the sink. That is mainly a matter of convenience, it seems. I'm just used to grabbing the container of dish soap and squirting. I even made some liquid by adding the dish detergent mixture to some water in an old dish soap container but I go through it so fast. This idea is not a dud, just one that didn't work out so great for me for washing dishes in the sink. It's awesome for the dishwasher.
Homemade laundry detergent: Fabulous! I wash my cloth diapers in this detergent only, and use it on our other laundry as well. I do love scented laundry detergent, so I do still buy Arm and Hammer, the natural kind.
As I have put these ideas into practice in my home I have found myself making fewer and fewer trips to the store for paper and cleaning items. That is a huge plus in my book, along with the savings.