This is what Windows 8.1 looks like without tile gradients.
Here is a quick mock up to show what the Windows 8.1 start screen looks like without tile gradients.
and here's what it looks like now.
Granted, it's subtle. You can see the difference a little more easily by viewing this gif (click to enlarge/start the gif)
or by going to the imgur link below and switching between the two pictures. The imgur link is obviously a lot higher quality.
Personally, I really prefer no gradients, as I don't think it's very metro at all.