It's obviously not teleportation, as it's not instant, and you can see the sound wave she made when she landed, it's just invisibility, maybe that's where the optic camouflage comes from, from Quiet.
It looks freaking amazing though, and I can tell Quiet is going to be a badass, couldn't care less about the clothing "controversy", her design is great.
And when she gets her eyes all dark, that **** was intimidating.
With the ugly ass design choices in Arkham Knight, I'm definitely more excited for MGSV now.