I'm a slow drinker and my tea stayed hot until it was finished! Almost TOO hot at first (burned my lip)! The double glass wall really works - even though the outside cools to the touch, the liquid is still warm with the lid left off for over 1/2 an hour. Only improvement would be the strainer; because of where the tabs are, loose tea falls through the holes. It was a bit of a challenge to get the tea infuser part out as the metal is tight to the glass walls, otherwise, a great product.
Only question I have: is the plastic in the lid BPA free?