The interface of Windows 8 Metro has been an innovation in the world of Microsoft operating systems so radical that I found people who liked it and others who simply are not used to this development.
Both groups still have the ability to customize the look using some themes for Windows 8 Metro, but that's not enough for you the good news is that they are proliferating apps that let you adjust the colors to your preference.
The emergence of such applications was quite predictable and surely you'll see increasingly sophisticated. Currently you have available as the Metro UI Color Changer, a small application that just takes up space in memory or on the screen, but useful enough to be able to change the main colors: color boot screen and login, background color or boxes or 'tiles' of the interface.
Logically, you can change only the items that you prefer, for example you can adjust the color of the home screen and leave the rest as is. As a bonus, have a button that allows you to restore the colors as if they were at first not stay after experiencing convinced by mixing colors you've chosen.