I was introduced to this game by a friend when we played a three person DS Download game. It was such a blast that I picked up my own copy. Multi-card play is much better, with the greatest additional feature being that you can save a multiplayer game. I've just ordered two more copies just for this reason, since my gaming sessions (3-4 hours) would really end prematurely when we cannot save.
Single player is still fun, but the AI does noticably cheat. That might be necessary, however, since it would really be too easy to win if it didn't. After only a couple days, I can beat the "normal" difficulty but still have a close game.
I really would recommend this for multiplayer, even if everyone else just downloads from you.