The KitchenAid ice cream maker is an attachment for KitchenAid stand mixers. It comes with a bowl and a paddle.
The bowl is a gel-filled canister that must be pre-frozen a minimum of 18 hours. Just like with any other electric ice cream maker, once your canister has frozen long enough, insert it into the stand mixer with the paddle, turn on the mixer and pour in your ingredients.
A few design comments: How to attach the paddle isn't all that obvious; be sure to assemble the thing before you take your canister out of the freezer. Also, it would be nice if the bowl came with a cover to minimize spills – if you make a full 2-quart recipe, it is likely to overflow.
Another lovely feature of this machine is the ability to control the speed of the paddle. This lets you decide whether you want your ice cream fluffy or dense or somewhere in between.
For those who feel the price of the KitchenAid ice cream maker is a bit high - considering all you're buying is a bowl and paddle - the big plus of not having another large appliance to store is worth the extra cost. If you already own a KitchenAid mixer, you just need to find space for the bowl (preferably in the freezer, so you can make ice cream at a moment’s notice) and for the paddle.