Make sure you're using this product properly because it works!
The negative comments are about applying pressure.  You don't need to apply any pressure -and that's why it stops working.  The idea is that it is skimming the surface of the callus removing it slowly and safely. It captures the dead skin inside the unit, so there's no mess.  You can do it while watching TV without any residue, just moving it slowly back and forth over the callus.  Then, you empty it!  I've been using mine for a few years now - still works great.
Rating: 5 stars