I don`t know why, but most of designers used to think about background as white, grey or black colors only. Maybe because they are afraid to try something provocative or give too much attention to background.
Yes, it is true that background should be used wisely. But we are not limited to these 3 colors only! If we were limited, than what`s the point to hire us, right? Developers can go ahead and use templates for most UI design products.
I have selected great example on how to use other than standard colors for your background. And this creates even much better result, than with white.
The composition feels light, soft, playful and so friendly. And that is only because of background color and great phone frame combination.