This actually looks really fun and I would love to play a shooter on 3DS that implemented these controls. This would also free up your hands to use all of the buttons, unlike the current DS setup of only being able to use the touchscreen, dpad and L button.
From: KingDavidxx | #010
The gyro tilt aiming is pretty cool, but I think it might not work well with the 3d screen since you need to have the proper angle to get the 3d effect. Or is the 3d viewing angle actually pretty wide? I haven't seen it in action yet.
Nobody remembers this, but just because the system supports 3D does not mean every game needs it. I don't think 3D is essential to an FPS, in fact I believe it would be detrimental.