My first version was a bit tight, but I joined Slimming World in September as you might have read on my blog, I've now lost 12 pounds in total since I joined. I decided to make the same size and as you can see it's a much looser fit on me! The material is also a looser weave man-made material that I picked up at the Knitting and Stitching Show and the dress is much more drapey as a result. The choice of material is really important for this dress and I think you should avoid anything too stiff.
I also used interfacing for the facings which the pattern doesn't mention as otherwise I think they would be a bit floppy. To be honest something funny happened with my darts on this one, and they don't quite line up, but I don't think that anyone else would notice. I kept the long sleeves on this version which I really like for the winter. I also made a button loop and fabric button rather than a hook and eye, although I think that I could omit the back neck opening totally next time.
I can see myself making this dress again as it's a quick and easy make. Have you made the Ultimate Shift Dress?