At first, I thought I could use a flat eyeliner brush (meant for gels/creams, which is what I use for brows) the same way as a brow brush. No. Eyeliner and eyebrow brushes for me are not interchangeable. Even the flat ones are just unacceptable to use on my brows- way too harsh looking, too flexible, too much product, etc. This brush as example, is almost too wide to dip directly in my brow gel pot. But it's very firm and makes a nice width for my brows- not too thick or thin.
Overall, I like this brush. It's a good solid brush- it's not exquisite or anything, but it's not a big investment anyway. I like the shape and the density, and its stiff but not hard, so its really easy to use. I rotate my brow brushes so one doesn't get used/washed daily, but this one has had 2-3 washings a week for about a month now, so I'm happy with it.