I have been playing (heavily) this game for the past week, in a hospital. The guy next to me had a DS as well, so we did a few matches, plus I couldn't stop playing it in single player.
It was great to be in a room with someone who shared my passion both for videogames, and this particular game, in a relatively troubling experience. We played it while we were waiting to be sent to some treatment / exam, so it helped us keeping morale high.
My only complaint is that it crashes too much. In a week I had it crashing on me once in multiplayer (single cart) and twice in single player. I didn't expect that and it's been disappointing (please do better testing next time, ppl).