I have thought about purchasing this for some time.  Now that I work from home, I like to enjoy hot tea while I work.  I wanted something to keep my tea hot throughout my work hours.  I used it for the first time today and was disappointed with in minutes.  I sat my cup on the hot surface and after lifting the cup for the first time, the teflon coating came off.  It seems to peel away with each lifting of the cup.  It has been keeping the tea warm but not hot, but it also seems to vary throughout the day.  Maybe my expectations were too high.  It keeps my tea warm but not at the temperature I expected.  I have to cover the cup to keep the heat contained and I feel this should not be necessary.  I do not think mine is defective but will continue to use it throughout the day and see if there are temperature changes.  Not giving up yet, but I am disappointed at the small pieces of teflon I am finding on my desk, especially since this is day one of using it.   Thanks