I am surprised to see the colour for the mug is blue as blue mugs are not as common as the red or yellow ones. It has the LEGO logo on the inside bottom just like the minifigure ones. I don't think the mug itself holds much liquid but it is still a great item for any LEGO fan! It is also available in Transparent purple but there were not any of them at my local LEGO store. In my opinion, I would recommend this mug and if you really want one I would go to your nearest LEGO store to get one asap because they are currently sold out online. You can view the product on S@H here.
I have taken some more of my own photos of the mug below: