Quality brush
This is a quality brush.  I try not to over-five star everything.  The main issue isn't the brush's issue - yet - but I would strongly recommend before using this to ensure your drill's batteries are fully charged.  I store the batteries charged but over time the power drains from them.  I don't think the brush usage is the issue, but because of this I didn't really get to clean much with the brush.  Recommend you just hit the worst spots with the brush.<br />In terms of usage, it did fine getting into the grout.  It even peeled this covering on the (cheapo) tile so it definitely has some power behind it!
Rating: 4 stars