I've played the card game a couple dozen times now and the payoffs are WAY out of proportion to the hand you draw. For example, I drew a pair and got $20. I drew a royal flush and got $220. Anyone who plays poker knows the odds of drawing a royal flush are far less likely than of a simple pair. And yes, as the OP noted, there does seem to be a pattern to the hands. Four of a kind is a bit common, unlike in a real poker game. So far, I've not seen any payoff larger than the $400 you get on the slots.
http://i.imgur.com/aKUb5NH.jpg