The new operating system seems to combine the best bits from both the iPhone's killer aesthetic design and Android's highly functional layouts.
The new Firefox phone is based on HTML5, a web-based development language that powers applications that run in mobile browsers. It's built on Mozilla's "Boot to Gecko" project, which will be adapted so that all of its phone features are HTML5 applications.
Like Android, the Firefox mobile operating system will be open source — meaning developers will be able to access any and all information about the operating system they need to build killer apps. Firefox and Mozilla are absolute darlings in the developer community.
TechWeekEurope also has a huge interview with Mozilla Europe's founder Tristan Nitot, which is worth reading.
Here's a picture of the Firefox operating system's lock screen, loaded onto a Samsung Galaxy S II. This isn't the phone that the operating system will actually land on, though.