I got this with my Glossy box a while ago now, At first I was disappointed but I thought I would try it and give it a chance.
The angled brush is so easy and quick to use personally I wouldn't change the brush its perfect to get the sharp edges and fill the brows in.
I use the bottom left one I think the others aren't the right colour for me the top right one is very dark but works well as a soft eye liner.
Here's how my brows were before...
And the result after..
As you can see there a lot more defined and look better structured. After using it a while now I think it always completes the look when I don't use it I feel like my look is unfinished and messy, It gives you a stronger look and doesn't look like you've done anything, it just looks like your brows are naturally that neat. :)