All this time people have been complaining that the Wii's graphic capabilities where lacking. Are we now going to get a line of people complaining the Wii U's graphics will be too much? Ah, it never ends.
But to address what I think you're really talking about: the Wii U is a completely new system and will not be compatible with the Wii, i.e. you will not be able to play Wii U games on the Wii. If you want to play Wii U games, you will need to own a Wii U. You will, however, be able to play Wii games on the Wii U and use all the Wii peripherals.