My son loves these crayons too.
Their size and unique shape make it easy for him to hold onto and write/draw in the correct form, or as close to it as possible. When he uses regular crayons he just grips it in a fist and goes at the paper in a stabbing fashion. With these crayons he still grips them in a fist but is able to use it in a way more natural and similar to the standard writing motion.
They came in a convenient thick flexible plastic type bag that folds over on to top and closes with a push button. The crayons are thick and the shape makes them stackable. My son had fun just using them to draw and as stacking toys. He also used them as toppling towers so while they are a whole lot thicker than regular crayons they are not indestructable. He's already broken 5 crayons within the first few hours of playing with them and was clearly upset. If he didn't destroy them so easily I would buy him another pack in a heartbeat. Maybe when he's a bit older and hopefully not so destructive.