I saw this and immediately thought "Takoyaki!!", which are little dumplings with bits of octopus, other seafood, or whatever you want in the middle.
I am having some trial and error with this. The batter isn't as thick and doesn't have as many eggs as traditional cake batter, so I'm finding it sticks to the cups even with oil. Still,even my first attempt turned out tasting good and reasonably spherical.Plus, 20 dollars is hard to pass up. The size is not overly large, either, so stashing it in a cabinet will be easy even in a smaller kitchen.
Pros: small size, easy use, cute color, decent price
Cons: I wish it had more cups,perhaps 8 to 12.