I tried the Vivi jumpsuit on at a boutique in size medium (they were out of small) but the waist gapped badly for me. I passed on buying it but I couldn't forget about it . I finally bought the jumpsuit directly from Velvet and I'm so pleased!
I'm 5'6" and about 135+, usually size 4 or 6, small, denim 28. Even though I'm not very tall, I have a long torso, which makes jumpsuits tricky.
I ordered medium with the intention of having the waist tailor for a better fit. To my pleasant surprise, the waist in the jumpsuit I received wasn't as baggy as the jumpsuit I had tried on in the store, and using the little side ties to snug it just a bit was enough to eliminate the gap.
The fit is overall a little loose, but to me, that's linen.
Rated 0 on a scale of minus 2 to 2, where minus 2 is Too Small, 0 is Just Right and 2 is Too Big