Great stuff, glad I came across this instead of using regular liquid soap. Seems much more effective and gentle, which is good, since makeup brushes can get expensive!
While this is priced a little high IMO, a little goes a really long way, and the bottle should last quite a long time, even though I try to wash my brushes weekly.
To use, I put a small dot of cleanser in my palm, wet the brush, and swipe/rub the bristles around in the cleanser. The cosmetics colors immediately seem to jump from the brush hairs into the cleanser! Then I give a good rinse under warm running water, and dry the brushes laying sideways over the edge of the sink (so the bristles don't sit in a small puddle of water, which I'm told can affect the glue holding the brush hairs in place).
Also, if you're more of a "soaker" than a wash-and-go kind of person, I would not recommend soaking any brush in a cup with a few drops of cleanser mixed with warm water for more than a few minutes: again, it can affect the glue holding the brush hairs together.