I put one on escape and one on pause, I absolutely love them. They're entirely unessesary and frivolous but I had rewards point about to expire and I don't regret picking them up at all.
I'm sure with time they'll deteriorate, but that's the case with all silicone type products.
Good, but deteriorates on the paw pads relatively quickly.
Extremely adorable, but the pads discolor from use quickly if not cleaned daily. Also they eventually flake and get rough to the touch compared to the initial soft feel. If you do get these, put them somewhere on your keyboard where you won't rub it constantly.