I'm gradually working my way through these American Girl patterns. They really do look lovely when they are made up. In my opinion though, you have to have quite a bit of dressmaking experience to use them. I like that you can print the patterns onto plain printer paper and cut them out. This makes it much easier than using the tissue paper pattern pieces.
Amongst my craft stash I have a lot of cotton fabric with small prints so these are perfect for this small sewing. I tried using Velcro as the fastening on the back of the dresses etc but didn't like it. Then I used part of a zipper on one dress. This worked quite well and I will probably do this again. Buttons with loops made from thread work ok too but my favourite fastening is to use plastic snaps. I've used the sew on ones and, as soon as I can get some, I intend trying the snaps that come with the applicator, I think these should work well.