The other day I picked up this usb coffee warmer for $4.99.
I figured “hey its only 5 bucks, why not ?”.
Well the plate does get warm and if you pressed down on the plate you would might burn your finger- if you held it there. I would say that it only keeps your coffee to about lukewarm temp.
Now having said that I have only used it with ceramic type mugs – so it may be different with another type of mug.
Bottom line – yes (somewhat) worth the 5 bucks but I wouldnt shell out a dime more for this particular one.
“Drink well, my friends”.