Quite clever, but needs a flat surface for it to work effectively, so it does not work on wood, cork, but works well on laminates, metal, marble, glass.
Getting the lid on properly is quite tricky, and, it has fallen off a few times with contents.
The problem is if you fill the cup too much, it seems to interfere with the lid. It feels like the lid will break.
It's a good talking point, it's fun (when sealed securely) to place it horizontally on a laser printer, or a filing cabinet.
Mr.G, London - 10th January 2014