Sorry but I don't like your design:
1. Why 4 columns? Tiles will look too small on 4" or smaller phones
2. What happened to the space between tiles? there is an space for some reasons, for example, little tiles are easier to "touch". Without the spaces, it is easer to touch the next tile.
3. Each tile with different background color? what about personalization?
4. Well, the top bar is the only thing I liked.
I love the WP8/8.1 home design because it looks great but because there are some guidelines for usability, the space between tiles, the size of the tiles, the columns, etc.
EDIT: Your design with some modifications, but IMO the Cortana tile is too big:
