Watch the video at 02:45. The performance is horrid. I can’t believe Samsung shipped it like that. Even if it worked correctly, I remain unconvinced multi-window experiences are enjoyable on 10 inch, and smaller, tablets.
However, I’m excited to see the Windows 8 implementation of dual-windows in action where you split the display not in half, but leave most of the screen to the primary app and reserve a skinny column for the second app. As developers have to specifically customise their apps to display appropriately in the small one-third width column, it might succeed where traditional implementations have not.