Hi there
I was lucky enough to realize something was wrong, my semen level dropped considerable but my libido didn’t, my hair grew thicker and more then evern before. I used Propecia for 2 years and only very slowly did my semen level drop, I didn’t think about it that much and honestly didn’t notice that much until my GF asked me about it.
Well just a general warning! I’ve been off the drug for a month and my semen levels are up again but I guess I’m lucky then to have recovered.
I just wanted to add to all the posts here that this drug is not safe to take and there just seems to be way more men suffering some issues then I believe the manufactorers intended. I don’t think they wanted to do anything but help men get their hair back but the warnings that come with the drug must be updated. This drug has way far reaching effects then the manual describes.
We men suffer way more quietly then women do and feel ashamed to talk about these things so I think only a fraction of men are really reporting the drug changing them.
I’m off the drug and my hair can fall off 
I prefer to remain fertile and generally healthy.
Good luck to you all in your recovery.