The shape was kind of a gimmick, building on the legend that Django Reinhardt used anything as a pick, from bits of haircombs to trouser buttons.
The material is nitrocellose (called Viscaloid), so I would keep it away from flames.
The print, a line drawing of Django's portrait on one side and four button holes on the reverse, wears off very quickly.
So why rave about a big plastic coin?
Well, I use expensive shaped gypsy picks in exotic materials (Dugain and copies) for playing with a fast and heavy downstroke. And I can't get along with flimsy plastic picks. But this one seems like the perfect marriage: a bit lighter than the gipsy picks, but still stiff enough to have enough control and volume.
I even use it on a mandolin!