You know there have been a couple of comments on "roundness." I never really thought about it before, but I can see how if you expect to carry it on your shoulder rather than on your arm, it would give the feeling of additional bulk.
I rarely use the shoulder strap because of my neck/shoulder problems and when I do it's just to facilitate carrying something else for a short time, but I do think, in general, skinny minnies would like this style better just because of the shape of it.
Actually, if one were planning on carrying it only on the shoulder, I wouldn't like it as well or suggest it because it loses that furtune-cookie shape when carried that way.
That said, for me, it is THE perfect bag!