I have read some positive and negative reviews of the Maximum Coverage Concealer Brush, and I'd like to throw in my 2 cents.
This brush does pack in a ton of minerals into one place. I really like to use it with a base shadow, Butter Cream by Earth Angels Minerals, all over my lid, and under my eyes. Its thick application is great for areas that need concealing, or brightening.
One reviewer said that it can have a tendency to look harsh, and draw MORE attention to dark circles, etc. I would say that it definitely can do that, and one way to avoid that is to use the Maximum Coverage Concealer...