14 DAY TRIAL // Ubuntu for phone has already amassed a large number of very interesting features, but the developers are still adding more eye candy for users.
Canonical has been working on Ubuntu for phones for more than a year and they have made some great progress. The system is now considered stable and it can be used as a regular phone. It's still not up to speed with the apps, but it's getting there.
Ubuntu developers are also hard at work on Mir and Unity8, but they also found the time to implement a great-looking app switcher. It allows users to see a carousel of running apps before choosing what to bring forward.
A developer demonstrated a while back that it's even possible to have the app running when they are displayed in the carousel, although that will not be an enabled feature.
Ubuntu developers are pushing new features all the time and the Ubuntu Touch project is now the focus of the entire team. The first Ubuntu phones should be ready for shipment in the fall of 2014, but you can test it right now on any Nexus 4 or Nexus 7 tablet, if you really want to give it a try.