Just bought Casey a Buster Food Cube (Mini). He's such a delicate-behaving dog that the regular-size ones, which Jake has no problem with at all, were not tumbling and rolling for him. He still thinks a lot about the process, about where everyone else is, about what he'll do for his next vacation, about whether the furniture needs rearranging, about the best color scheme for spring fashions, and so on in between pawing or nosing the cube around.
My dogs love these things. They are particularly good for days when I don't have much time to spend with them (because, for example, I'm doing critical activities such as updating their Web site) or it's raining and nasty out so that they're not getting much exercise or stimulation. Jake, Tika, and Remington all work(ed) hard at the cube until the food is gone, so they're typically panting when they're done. At the "easy" distribution setting (which is all I ever use), it takes maybe 5-10 minutes for them to empty the cube.
Jake relies primarily on flinging the cube behind him with one front paw so it tends to crash off of walls and furniture. Not for use when you've got your antique crystal collection set up in the middle of the floor. Remington relied primarily on nudging it gently with his nose to roll it all around the room, using his paw only when he'd get it into a corner. Tika's more the nose type, too, but uses her paws more than Rem did. All find it easier to use on the carpet than on smooth floors. And I prefer lighter or more solid color carpets, because otherwise little bits of food hide in the pattern.
The bonus entertainment value that you get from the food cubes is that little bits of food end up rolling under various piece of furniture and the dogs don't always find them while doing their post-cube room evaluations. Then, hours, days, or weeks later, one of the dogs will go nuts trying to crawl under the couch--or the stove--