I successfully ported my puzzle game Turky on the Run to BlackBerry 10!
The process was quite simple (even using the command line approach) and dealing with RIM was very straightforward and fast so this really seems like a good platform to develop for (really, I found the submission procedure much easier to follow and understand than for iOS or W8. Besides, signing for a developer account is free!)
One warning though: at first, I submitted my game with letterbox scaling and it was rejected for that very reason (they don't want sidebars). Be sure you submit yours with the right resolution covering the whole screen!