Custom start screen background
A few people have complained about the lack of customisation here so I thought I'd see how plausible it would be.
Here's the start screen with no background, and then with a custom background.
So the problem is obvious - the visuality of the tiles is seriously impaired with a busy background.
So here's my take. Over the background goes a sem-transparent layer of your theme's colour.
You want to be able to see enough of the background, but also see the tiles without distraction - so behind the tiles the theme colour is intensified.
One of the cool things about the start screen is the background moves a little as you scroll - so I've compensated for that too. Rather than displaying the whole image, we're seeing more of a zoomed-in view, which then scrolls as the screen scrolls.
This could work quite well for lower resolutuon wallpapers, too, which usually look terrible. But the overlayed colour would likely hide pixelisation.
So what do you think?