While monetarily the subscription is stupid expensive, several years ago blizzard added a way to pay in-game gold for an item that's worth a month's game time.
If this person is putting off eating to play they're would be considered "hardcore" in my opinion. And if that's the case, they probably have way to get around the monthly cost, or they could have bought mass time all at once on discount.
I enjoy it a lot. It does use poker hands to score, but there are so many layers on top of that. From which of the decks you start with (i like the deck that only has 2 suits, makes making flushes real easy), to swaping/adding/removing cards that don't fit what jokers you have, to manipulating how many of certain cards you have (I've had decks with 10+ 2's before).
The only information you really need is knowledge of how to make poker hands and some basic math skills. Great for low stress gaming imo.
I've played enough D&D to know a Dragon hiding themselves with Illusion magic when I see one. Just leave your gold as tribute and don't look'em in the eye.
And coming this winter, mandatory claping.