I Loved the idea of the cup, but it was a little heavy and akward for my son to hold.  He always needed two hands to hold it and get it up to his mouth.  If he used one hand, the cup would fall to one side and then spill or leak.  The mouthpiece was flimsy.  I think there should've been a more sturdy mouthpiece that kids can't chew through.  Also, my son chewed on the mouthpiece, which was real rubbery, and it broke off into many little pieces that I was afraid he was going to choke on so I threw the cup away.  The price was a little high and I had high expectations since I loved their...