The best part is all the cute puzzles it includes. Many of them have you use the device in some ridiculous way. Like, you often have to blow into the mic to simulate blowing out a candle, or you occasionally have to fold the device shut. Silly, but, well, silly is a good thing sometimes.
The main bad side is that the multi-player minigame is terrible when playing against complete strangers. What happens is that if you are about to win then people quit! When they do this, you don't get credit for the win, and neither of you gets a chance to trade items. Sucky sucky.
You can set it up to play with only people you know, though, which is nice. To that end, my friend code for Zelda Phantom Hourglass is: 1504 4505 4192. If you catch me online, let's play!