I like this brush, I don't have a lot of eye brushes because eyeshadows always crease on me (I've tried almost every eye primer under the sun, particularly the popular ones). I tend to just stick to eye detailing around the eye and lash line.
This is quite a thick smudge brush and I use it to pick up and pack on eyeshadow on my top and bottom eye lash line. It's a firm yet soft bristles. I also find that it smudges the eye liner well.