Kid Icarus is great.
Zelda is the same old thing with less traveling in between menu screens.
Haven't played Metal Gear, I hear it has frame rate issues, though.
NSMB2 is more of the same, but has some unique ideas. DLC is worthless.
Tales of the Abyss also has some frame rate issues, but it's good.
If you don't own Pushmo and Crashmo, you're not playing a 3DS correctly.