"Fantastic Super...." ?.... Not really; they're far too light and won't stand up on anything other than a perfectly flat surface, and even then, if there's the slightest breeze - Forget it.
My tip: Drill a 5 or 6mm hole in the bottom of each one; inject a dollop of mastic into them; then seal hole with a bit of tape. At least they stand up, now. More importantly, my children can stand them up without getting totally frustrated.
As for the balls: they're off balance, so won't roll straight; which makes it rather challenging (for want of a better term !).