ok, I've made this a few times. I Think I made the strap drop around 18-19 inches. The depth is around 2 inches, I believe. I kinda built my own pattern from reading her tutorial and honestly can't recall what all I changed for length and depth, but I don't think it was too much. The bag is a nice size. I also probably did my own thing for pockets. I think it's a great size for day trips as a diaper bag, and for a daily use handbag.
The straps: The upper 10 inches I narrowed to make the way it hangs more visually appealing.
Body of the bag: I use stabilizer on at least the exterior fabric to give the bag more body, too.