I've found mine to be excellent compared to my old Mk2 TDI - in some cases the demister actually made the screen worse! I had a passenger once who witnessed it too - we couldn't believe it.
It does surprise me how easily the Mk2 and Mk3 mist up though, especially overnight.
I've seen some suggestions of running max Aircon for the last minute or two of your journey before leaving the car overnight to dry up any moisture inside the car.
Silica gel bags have also been suggested, something I considered for my Mk2.