I have been using this mug for about 3 months now. I really like it alot although there are just one concern... The rubber O-ring on the lid that is essentially the spill proofing comes off the lid VERY easily if you are not careful when hand washing, therefore allowing your beverage to spill all over your car seat as it did mine. Now that I'm aware of this it hasn't been a problem since. Also, the claim of 8 hours of keeping your coffee hot is not realistic unless you work in a heated area. If you work in the cold it will go for about 2 or 2- 1/2 hours. The one thing that I didn't like before ordering is that it is only 16oz. HOWEVER, what I have found is that now my coffee is staying very hot for a longer period is that I drink it slower & the 16oz is sufficient. Overall It is the best mug I have owned & would definately recommend!