As for why it's so great, well, it checks all the boxes: It goes on smoothly and sets pretty quickly, leaving minimal marks from the tips of lashes. It lasts all day without flaking (this is huge, because flakes are major irritants), and best of all, you can build it up without lashes feeling brittle or dry (again, irritation central). And the brush? It's full and fluffy in the best way possible. One more thing: Don't let the waterproof accolade throw you: It's not like the car-paint-inspired formulas you may be used to; it stays on really well, but comes off with a little micellar water.