UI was built off of the WPF Metro Template, which was developed off of Assembly.
A preview of what you're downloading...
This shit is licensed under the DBAD license, so don't be a dick and steal it, etc.
Have an issue? Yeah... You're probably not alone. Report it on the Issue Tracker.
The Segoe WP fonts, Metro Design Language (now Modern... lol), etc used are registered Trademarks of Microsoft Corp. Blah, Blah, Blah