Mirroring

Hi,

Can't get iPad mirroring full screen through apple TV (new HD and IPad3). Mirroring reduces the image by 20%. Told by genius at store that this is an issues of resolution and doesn't work although some apps do allow full screen reproduction without issue and it's apples own operating system at fault.

Staggered if this is true as air parrot on a Windows Laptop works perfectly with the apple TV at full size. As does a colleagues android app on Samsung galaxy!

Is apple really this bad?