I'm so impressed with this. I got the dark brown, which is a true deep brown and perfect for me. That in itself is great, as the eyebrow pencils and powders I've tried in the past have all had a reddy tinge, which just looks terrible with my black-brown hair. The formula itself is surprisingly liquid and very pigmented, so a VERY light hand is required, otherwise you end up with dark globs and an uneven finish. (That said, it's really easy to whip off again with a moist cloth if you make a mistake.) If applied lightly though, the firm brush combs easily through the hairs, depositing the gel uniformly, and it's short and angled for easy manoeuvring. A single brush-through gives all my brow hairs a coating, making each one look thicker, and it deepens the colour too, which adds to the look of overall fullness. A second sweep gives me a more dramatic look. I love the buildability of it. And it seems to dry almost instantly, basically setting the brows so you can rub your fingers over them without removing any of the product.
I have quite sparse brows at the outside edges, and this fills and blends so that my whole brow looks more uniform. If you had no hairs at all to build on though, you'd obviously need to pair this gel with a pencil or tattoo pen or whatever.
I want thicker brows, but I do like them to look naturally thick rather than obviously painted on, so for me this formula is wonderful. And now that I've mastered the application, it takes me literally seconds to quickly brush through my brows and be set for the day. Oh yeah, and it lasts all day, not budging from sweat or humidity or anything, until I decide to wash it off - with just my normal face cleanser. No special makeup remover required.
I use this along with an eyebrow pencil, and this is great to shape and set my eyebrows. Seems to help my eyebrow pencil last longer.