We've got a 2 player poker game (iPhone, iPad) and we've spent a lot of effort to make it look and play like real cards.
I wondered how it might look in a "flat" type UI. I didn't do everything in the UI itself, since in a flat UI there's usually gestures too. You'd drag over from your stack towards the bet to increase the bet, and drag up from the bet to the pot to make your bet.
The card actions would be like they are in our game now, drag the cards up to fold. The iPad app has more space so shows your stack, dragging that up goes all-in, which would work with this too.
I'm sure a real designer could do better, but I think in some cases like this the realistic look will win. (Probably because it's a game and cards are flat real-world items.) Looking at the realistic picture, I know it's a card game immediately.
Updated since I got thinking how other games or apps might be done.
Internet, GO! What would other games look like in this style?