Mozilla has been trying to get into the mobile space for a long time. Check out this item from February 2008:
Mobile Firefox for Linux, Windows Mobile By Year-end
Businessweek provides a nice overview of Mozilla’s 2012 efforts.
Mozilla’s Catch-Up Strategy for Mobile
As for me? I rarely use Mozilla on the desktop these days and tried but do not use its Android beta offering. The native browsers for Android, iOS (iPhone/iPad), and Windows Phone are pretty good right now. I’m not looking for an alternative mobile browser.