I also found that the original straps I drafted are too short. They are an alright length for someone my size to wear but don't allow for much adjustment and would probably not be comfortable on someone with substantial shoulders. I've made the pattern piece 3 inches longer now.
I didn't like how the zipper pocket in the inside turned out in the prototype. The zippers I bought are too thin to make the zipper look nice on the right side without any extra bits added. I bought some brown bias tape so that I could just add some seam allowance but then I decided it would be nicer just to make a welt that covers the zipper. Overall I'm pretty happy with what I came up with. Now I just have to make it like 15 times, and make some other items I can sell too.