Quick bugfix: It only seems to work if you include the "www." in the URL of the page. Why not just ask for the page-slug instead of the full URL?

EDIT: I can see this being really useful in a "opposition research" sort of way. It would be great to be able to view/compare multiple pages at the same time, and then try to highlight where one is going better than the other.

For pages that you manage, it's really not that useful when compared to the powerful analytics Facebook already provides through the insights tool.