The UI appears to be clean and sleek - I like it, except for a few things:
- the text are too small (what are the screen dimensions in your render?), there is too much empty space in the tiles;
- blurring of the background image should be adjustable, not all users would want a blurry background image;
- the lock screen image needs to be dimmed a bit, if not have the same blurring option as in the start screen background - notice how it's hard to see the quick notification icons in contrast to that blue green-tailed peacock.
- the battery icon should either have the battery icon that represents the amount and charge OR have the numeral charge value, not both at the same time (redundant) - notice also that it says "100%" but the battery icon is almost empty.
The implementation of interactive live tiles is interesting, but that's a question of hardware/software already, not design.