It fits my current knitting project (socks, which are almost finished by the way) perfectly, I have room for the yarn, sock-in-progress, finished sock and the pattern. So cute.
The only mods I made were to use craft felt as the stabilizer, and to lengthen each handle by two inches. I also made the boxed corners of the bag 1.25" instead of the 1.75" (?) suggested in the pattern.
Here is the bag shown with a ruler for scale.
I have a little sewing experience, but I haven't really gotten into as much I have knitting and a few other crafty things, mainly because I have a fairly finicky sewing machine. It does its job though, and I'm not really keen on buying a new machine since I know that at this point in time, I wouldn't use it enough to offset the cost.
I realized about halfway through the project, that I was using the wrong size needle, which probably contributed to most of my problems, I also need to do a little tension re-adjustment before my next project.