Mer has an advantage that it's not corporate controlled, and doesn't have political shortcomings of Meego which died so easily the moment Nokia pulled the plug. Tizen has the same risk as Meego since it's at mercy of Samsung's and Intel's unstable moods, and history shows they aren't really trustowrthy in regards of the platform viability. So it's good that Jolla decided to use Mer. Together with Plasma Active Mer will have a good starting pool of vendors using the OS.