The button to manually share a level up on Facebook is broken.
As of December 7, 2014, the manual share has been broken for a couple of weeks. When it says, "Great! You leveled up!" and gives the buttons at the bottom for "Share" and "Continue," the share button no longer works, but the continue button still does. I'm at level 15 and the last level I was able to share onto Facebook was level 11.
And FWIW, I preferred the heart system better. For a sports analogy, it was like in American football, where you're allowed three failed attempts to gain ten yards, and then bringing out the punter. Now, it's like having an infinite number of tries to score. The new system is less demanding and I've noticed an increased lack of self-discipline in my own efforts. Just my $0.02.
Lastly, thanks for such an excellent free program.