I suppose it is a perfectly fine mug. It is well insulated. Under normal, non-traveling-in-the-car conditions, it is probably an outstanding mug. Only slightly likely to tip over because of the narrow base. The base is not actually narrow enough to fit into a cup holder in your car. The base tapers so if you’re stupid unfortunate enough to try to drive with the mug between your legs, should you shift gears or otherwise put the squeeze on the mug, it will pop up. Which *might* lead to a lap full of hot tea. Very hot tea. 
NOTE: There is a handy-dandy feature that allows you the perception of closing the lid, cutting off the flow of hot tea. This is for looks only. In practice, the hot tea will freely flow, independent of the position of the lid.
OK, I have to confess – after I took the pictures I threw the mug away.
Poor sad little mug.