In MGS3D DEMO, everything is doubled for me. 3D in the woods isn't a good idea.
And i didn't know 3DS could "pop out" things, isn't just depht?
Nah. From what I seen so far, there are two different 3D types used in the 3DS. One is the depth one that you're thinking of, the other is where they pop it out. Nintendo usually sticks with the depth 3D while the other devs go for the popping out 3D.