I purchased my One by One mascara a couple weeks ago and used it for about a week straight. I really do like the formula of this mascara. Many people prefer the falsies over this mascara, but I honestly think the One by One is much better. As far as volume goes, it doesn't do much in that area, unless you add bunches and bunches of coats. If you really want a nice, light, natural looking lashes, I recommend this mascara. It's lengthening and it separates your lashes very well. I don't really curl my lashes but I feel like the formula in this mascara lifts and slightly curls your lashes a bit too.
This mascara really does lengthen your lashes and with doesn't make your lashes look clumped either. Overall rating for this I'd say is 8.5.