My guess is that it's just thin card stock, and not truly playing card stock. I would definitely buy some but the conversion from pounds to American dollars, plus shipping to the states, would most likely make them prohibitively expensive for me.
Found a similar one on Amazon for about $10 with free shipping (Prime members). Only one review that stated that it was "garbage", but of course didn't explain why.
You know, that might be a good KS stretch goal for a deck with a really nice back design such as Ornate or Aurum. Maybe a desk notepad or individual sheets in a holder, with the deck back printed on one side of thinner cardstock, and the other side blank. It it were going to be padded, I personally think that padding along the short side (the top) would be more practical. A pad not quite as thick would be better as well...I think that the 52 sheet count is clever, but may be too thick.
First, please don't double-post. Just re-edit your last post if you have something to add a short time later.
Second, read this description quotes from the item's page:
52 specially commissioned playing cards with blank faces. Bound along one edge to make a pocket size book. These are made from the finest quality genuine playing card stock, and feel exactly like a deck of cards in the hand. The characteristic weight and texture is unmistakeable [sic], and makes a great surface for your thoughts, notes and doodles. The front card is printed with either an Ace of Spades or Queen of Hearts and the backs are either blue or red. Supplied in box just like the real thing.So there's no ambiguity about that - the pages are all playing card stock, not thin card stock. And if I'm not mistaken, $10 is a touch more than 5 pounds - nearly 20 cents a page is not a cheap notebook. As a KS tier reward, it would likely end up costing more than the pack of cards you're creating! And who would want a notebook with pages that expensive that can only be used on one side? It's more of a decorative design piece than a practical object.
I don't hate the idea but I've personally never had much luck writing on playing card stock (with any type of finish) with a ball point pen. Permanent marker yes but a pen is quite inconsistent, especially when forced to write microscopically.
If they use a smooth, unembossed stock, it would be considerably easier, especially if the stock is unvarnished. It would seem logical to make it as such, but when has logic ever played a part in product design?
EDIT: I looked at the closeups. You can't get a good clear shot of the pages, but I did see embossing on the Queen of Hearts cover. One could hope that was only for the cover, but knowing how playing cards are made, that's terribly unlikely.
SECOND EDIT: yup - the page that says "Don't forget the chips!" has embossing on the surface as well. Yeesh.