Thanks for all the answers!
@arc123:
I mean white pages or white areas of the screen are getting darker, like I you would expect it when changing the viewing angle, but in addition to this normal effect, white is turning very quickly in very small steps from redish to blueish and vice versa. It looks like those white areas are twinkeling or flickering from white into grey with a rapidly changing color gradient.
When I put the phone on the table and rotate it quickly, it completely goes nuts with a rainbow-like color effect show. Its like the LCD is on LSD.
And no, my eyes are fine and I'm not doing drugs
My iPad2 and all the other LCD-Screens I have are fine and doesn't show this effect.