I'm not 100% certain if it's still available because I bought mine a few years ago, but I think they might have redesigned it so that that back pocket isn't the mona lisa smile anymore, but rather extends the entire length of the cardholder. The mona lisa smile back pocket is really useless, it's not wide enough to actually put cards in without damaging / stretching the leather. It looks really nice because it emulates the classic flap but other than that, it has no function. The new design with the back pocket extending the entire length of the cardholder is a much better design because you can actually put stuff in it.
I don't have the regular shorter card holder so I can't compare. I like the look of it because it looks more proportionate than the regular shorter cardholder, but I also feel like there's quite a bit of wasted space that's unnecessary since the larger cardholder is taller than a regular credit card, and you wouldn't stuff it full to fill that space to prevent the the leather from stretching.
At the time I bought it, it was indeed a popular item that was hard to find in store, specifically because of the mona lisa pocket.
I did a quick google and found this review comparing the two designs: