Product review (4 stars): clever gadget.
I hope not to find out how well this works in a fire. This seems to work not with a heat sensor but rather requires flames to reach a fuse on the bottom.  this might very well prevent a grease fire from destroying a house.  A  heat triggered system that will also shut of your gas or electricity is quite expensive so this seems better than nothing.  Al the same I would recommend havng an ordinary fire extinguisher handy in your kitchen. You may well e able to prevent a fire from getting big enough to trigger this gadget. Just stand back so you don't blow flaming grease over yourself or the kitchen.