I was pleased to open these and find nice-looking mugs but I was far less enchanted upon reading that metal spoons are not to be used to stir contents.  I don't like to serve fancy coffees with a plastic spoon!  However, it does explain why the inside of many reviewers mugs were easily broken.  My coffee stayed reasonably hot and I did like the lightness of the mug.  I thought they were plastic at first.  I can't comment on durability but I won't even be putting them in the dishwasher.