It took a few tries to figure out how to get it just right, but I love this tool for getting a huge, ballerina bun! I watched the Birchbox tutorial a few times (as an aside, if you haven't already definitely check out the Birchbox hair videos, there are some really good ones) before I tried it out. What I like most about it is that it doesn't need to be perfect. You can have a few hair sticking out here and there, and it still holds your bun like crazy.
I can see that it would be harder to use with short or fine hair though. Also, my hair is REALLY dark, like espresso brown, so I have no issues with the color peaking out, but I'm not sure how it would work for people with pronounced highlights or lighter hair.