Got mine yesterday as well and watched it on a US PS3.
It is indeed a director's cut. There's new footage throughout the entire film. There's some extended conversation with Ranulph Fiennes, an extra bit of film where Richard explores a building they come across during the journey that has some beds and some canned food (if you've read "As You Do", this is the place where Richard finds his Taj Mahal loo), and there's an extra bit where Jeremy and James come across some sort of abandoned station (this comes after they find the abandoned plane, I'd assume it's the station the plane was taking off from when it crashed). Those are the major new pieces to the film, but as I said there's a lot of little tiny 10-30 second bits added here and there.
Pretty much every piece of music used in the original Polar Special has been replaced with some rather poor substitutes. It didn't feel quite as epic because of the poor music, but the the amazing video quality (and extra footage) certainly make up for it.