Just finished my margaret bag from here - http://http://www.ohfransson.com/oh_fransson/2008/11/margaret-sling-bag.html I made the cross-body style.
The fabric I used is a furnishing weight from Ikea and instead of the interfacing and interlining I used a single layer of thin iron-on pellon. The button is covered with the same fabric, fussy cut to use the seed pod design.
I added a key clip and incresed the size of the pleat slightly but otherwise followed the pattern.
I'll give it a test drive over the next few days, but found the pattern really easy.