Mario Land 3D is hella easy, although getting past Bowser in World 8 was a bitch. I cheated and used the P-Wing. But still, if you grew up playing Mario games from the NES through the N64, all the references to the old games are a fun touch, even if the fun only lasts for the first time you play it.
My brother got me Star Fox 64 for the 3DS. It was easy the first time I played it, but I had it on 3DS Mode, which may have been nerfed because I got my ass handed to me on N64 Mode. My Gyroscope may be off-balanced too, because I had issues using it and had to play with just the joystick. Still, fun game and Corneria is gorgeous on the 3DS.
My buddy and I are waiting for Shinobi. I read a review that said Ghost Recon is good, but haven't played it.
We need a 3DS Friend Codes thread, too.