Here's my experience for what it's worth (actually similar to Boberto's above). I started balding at 21 and it made me very depressed. My baldness pattern is NW4. I tried various things including buying fin/propecia off internet websites (something I can't believe I did now looking back on it). I'm no longer sure of the timelines involved but about 4 years ago, I started taking propecia regularly and started growing my hair a little longer. I've had great results, maintained a lot of my hair and my curly hair covers what's left of my hairline. Some people have even asked me when drunk, if I have had a hair transplant!
Anyway, I'm 33 now and married to a very beautiful woman that I have been dating for 10 years. Over this time, I has gradually lost interest in sex and it became a bit of a chore. I never had problems performing but I just wasn't that interested, I never had morning wood for example, but there wasn't some big problem in our sex life, we still did it quite regularly.
I put it down to getting older and being with the same person for so long, but about 4 months ago I quit fin as we are trying to have a child. The difference is night and day, I am waking up with hard wood, libido has really increased and I feel great. My original intention was to get back on the fin when my wife got pregnant, but this hasn't happened yet and the changes that I noticed made me realise the effect fin was having on me. I'm after reading various hairloss forums for a few hours this morning for the first time in a while, and based on other peoples experiences I havr some rapid hairloss coming my way unless I go back on fin. I think my front has already thinned a little. So, I don't know what to do now. I would avoid fin but I have a head shaped like a rugby ball so shaving it short is not an option!
Anyway, that's my experience
On aside note, it's depressing to see how little has changed in the hairloss world since I began reading hairlosshelp.com/forums over 10 years ago, the cycle of hope being given and taken away, continues