The first thing about these decks is the amazing tuck box, which is entirely unorthodox and very flashy - the cards actually rise out of the box as you open it. Then there's the design, which is exclusively for cardistry - the cards are identical on both sides. Next is the card stock, which is a very rare one from Cartamundi. These use a C9 finish, which is slightly thinner than the more common True Linen Finish B9 decks. While they are still slightly thicker than your average USPCC produced deck, but quite comparable, and this makes them more pleasant to use if you're used to handling USPCC produced decks.
Another difference is the embossing pattern used. Unlike the true linen finish of the B9 card stock, the C9 playing cards have a more traditional air cushion style embossing pattern, with small dimples spread out evenly on the surface of the card. This is a matter of taste, but I prefer it. However I have found that these cards don't faro easily, at least it's not very obvious whether they have a traditional or modern cut. But overall the handling is excellent, and I prefer it to the more common True Linen finish B9 decks from Cartamundi. A great cardistry deck.