I was fortunate enough to receive a sample deck from Adam. It will be different from the final product in that this deck was made by MPC and had a blue box and no extra cards, the final version will be made by USPC in a white box with extra cards. (I'll let you figure out what the extra cards will be!)
The artwork is attractive. There's no denying that at all.
I noticed that the backs weren't perfectly aligned when they were cut, allowing for some cards to have white spots in certain places and not other places along the edge, and in a manner that matched some but not all of the cards. It's not a very clean look - consider adding a black border at the edge of the back design to create a uniform edge appearance. A white border would be even better, since black borders do eventually chip and show the white paper underneath, but that might clash with the present design being so predominantly black.
I ran into a bit of a hitch when trying to play my current favorite solitaire game, Canfield (known in some places as Demon). I know there's the whole "guessing of the suits" gimmick, which is an interesting one, but there's a bit of a problem in that the cards are completely monochrome, with a single exception of a card with a seven-color rainbow on it. Canfield requires the stacking of alternating red and black cards on the tableau before they can be sent to the foundations at the top of the play area. Adding the complexity of discovering the suit to the necessity of arbitrarily choosing certain cards to be "red" and others to be "black" made the level of difficulty too much for a simple, fun game. As most solitaire games use this mechanic of a two-color deck, it means most of them would be very difficult to play using this deck.
For other games not relying on color, such as rummy or gin, you could use this deck without being driven crazy with interpreting the suits. But even there, it does add real complexity to the game itself. That could actually be a fun mechanic for a party game! If you know people who are into party games, this deck could be a real kick in the pants to liven up the party.
So, buy it as an art deck. Buy it as a deck for children to discover with. Buy it as a party game deck. Don't buy it for poker or solitaire. And a special caveat - when dealing with young kids aged about 5 and up, they'll identify pictures and phrases more easily than they'll identify cards, making them an interesting alternative to a traditional deck for use in certain routines. When they're young enough, all the Jacks and Kings just look like "guys" and they have a hard time telling the suit pips apart from each other, especially if they're the same color. This deck possesses NONE of those "drawbacks". However, there's one thing you might want to do - one of the queens is represented by the word "drag" and I don't know of anyone who wants to explain what a drag queen is to a child...
EDIT: I played a bit with the deck, just sorting the cards by suit - didn't do too bad, only had one misplaced card. The suits are identifiable, but it makes you think more than you normally would in order to identify them. Indices would be great, but would also ruin the puzzle aspect of the deck.