
Portal 2 will continue to challenge players to use portals to traverse rooms in unusual manners, such as flinging, in which the player uses the magnitude of the momentum gained by gravitational acceleration through the blue portal to cross a wide gap out of the orange portal.
Portal 2 is a puzzle game presented from the first-person perspective.
The goal is to maneuver the characters through a number of test chambers in the Aperture Science facility, traversing the chamber from the start to the exit.
It is definitly a mindfuck.. and if video games give you motion sickness then stay away from this one haha!
POSSIBLE SPOILER (not for the story but for the puzzles)Check out this video for an example...
http://www.youtube.com/watch?v=f5aYKuPG9OI 
at them when they get stumped.