At this morning's Sony TGS press conference, boss Shuhei Yoshida played PS4 launch game Knack with a DualShock 4 controller, but then paused the game to take over using the PS Vita TV system.
With a DualShock 3 controller he navigated around the PS Vita TV's UI, showing how items can be moved and started. It looks a lot like the Vita UI. Note that the DualShock 4 controller can also be used with PS Vita TV.
Starting a remote play application had the Vita TV connecting to the PS4 quickly, bringing up Knack on the screen. Perfect! It was very quick to connect, though he admits that being outside your home network would take a bit longer.
This remote play system is still in development, Sony says. They're aiming to have it ready for launch.