At that resolution it's still really hard to tell how much an improvement it is over id Tech 4. It does seem like there isn't much in the way of repeating textures which is nice. I just wish id's designers/artists wouldn't always choose such drab environments.
The marketing speak makes it sound like the entire engine was built from the ground up with the QW:ET Megatexture stuff in mind. I just wish we had a demo or actual game we could sink our eyes into.