The classic card game Hearts. You can play solo against three robot players. The robots are pretty good. Or you can play against friends via WiFi, Bluetooth and Game Center.
Game Center games feature voice chat. Talk to your opponents, keep your hands free for the game. Voice chat can be disabled if you like.
Multiplayer games can be suspended and resumed. Say you get a phone call, which forces you out of the game. When you restart Hearts Net later on, it will pick up the game right where you left off.
If you can't decide whether to buy this or not, have a look at Hearts Solo, my other game, which is free.
Many of my Hearts Solo players told me it's too easy to shoot the moon, so I upgraded my robots to be far more paranoid about that. Try it and see if they are better.
Card movements are animated. Works in portrait and landscape modes. Hearts rules enforced are exhaustive and complete. Scores are displayed hand-by-hand, showing progress over time. Very configurable. Saves your game between runs of the program.
For more details, see my website.