with the 3DS you recieve 6 cards (like playing cards). You put the card on a flat surface (preferably uniform) and point the 3DS at it (after entering the augmented reality program). Once the card is recognized, the game starts. First a box seems to pop out of the card (and yes you are holding the camera, so the card moves as you do and you can also rotate arround it). and then you have little targets appearing that you have to center on the screen and shoot, all the while the ground on the card is deformed so the stuff on the screen moves.
The novelty is really that the stuff that pops out is modeled in 3D and that the gyroscope in the 3DS "feels" your movements arround the point you are aiming with the camera, making it so the stuff appears to be really there, but not visible without the filter of the 3DS camera (if you see what I mean).
The little game ended with a dragon poping out his head of the ground and attacking me, I had to shoot arrows at the different parts of his head to knock it out.... which was done by rotating arround it (easy as only his head and neck stuck out of the ground).
This doesn't seem as a big aspect for adults, but there is definite potential to have many smaller games that kids can play with and have loads of fun. Well i'm an adult and I thought it fun so...
on the glitch part... well you need to keep the card in the field of view of the camera and the demo was done on a white surface... so it didn't glitch. I can't say what it would do on a superman bed cover or something...
actually sounds pretty fun. i hope nintendo and other companies perfect this because i would love to see some of the stuff they come up with *crosses fingers for zombie game*.