It may be different for other operating systems, but on my Windows 7 computer whenever I change the appearance settings for Tiles it will disable the "auto-hide" on my task bar.
It's not a big deal, I just need to go back and re-enable auto-hide. Although, it seems there should be a way to keep that from happening in the first place.
Other than that I wished that it better handled web page shortcuts. Those saved with Firefox as the default browser don't show an icon, and they give an error message rather than opening normally.