Marrow is a dusty purple shimmer. The shimmer is on the subtle end of the spectrum but does show up in most lighting conditions.
I used two coats to get bottle color. The brush on these is fine; I found the handle a bit stumpy but soon got used to it. Like some of the other premium brands, the part of the cap that shows is really a cover and pulls off to reveal the part you actually hold when you use the polish. Unlike some other brands, the Butter London caps have a label that tells you that.
Being a purple person, there was no way I was leaving Marrow behind, and it did not disappoint on the nail.