I saw that site too before I started taking Propecia, with the belief that those things probably did happen, but that it was a small percentage of men and unlikely to happen to me.
Well, I took it for two weeks, quit, and over two months later, I'm suffering from a multitude of the things these guys complain about... libido problems, shrunken/narrowed dick, sagging testes, prostatitis symptoms(frequent urination, difficulty urinating, yellow semen), devastating insomnia, and constipation. All of these problems appeared or worsened after I quit the drug.
That last part is what I did not understand before taking it... My plan was to take the drug and quit at the first sign of sides, which is what I did. The problem is that, sometimes your endocrine system crashes AFTER you stop the drug and that's when all the horrific stuff starts to happen. This is how it went for many on that site. There seems to be a predisposition to this "crash" which is independent of how long you actually took the drug.
finasteride isn't something you want to mess with. Most guys get away with it, but if you're one of the unlucky few, you might regret it for the rest of your life. That being said, the long term consequences of taking this drug are not known even for those who have minimal sides, and also many of those currently on the drug who swear by it might well be a victim of the post-finasteride "crash" once they eventually stop.
As for the site's membership, it's a very depressing place because there's no real answer to the problem, or hope for many of the members. Many people register and never post, or lurk and don't register at all. There's no telling how many thousands of guys out there are going through these problems but simply don't know of the site, or don't even associate finasteride with their problems because doctors and Merck tell them there shouldn't be any sides. I try to only go over there when I absolutely need an answer about something, as it's an incredibly discouraging place.
My advice is to shave your head for a couple of months and see if you can get used to it. Go to the gym, get in shape, and see if you can't make the look work. I know it sucks to be bald, but DHT is there for a reason and your hormones are NOT something you want to mess with just to keep your hair for a few more years at most, assuming the drug works at all. You don't realize how important your health is until you've lost it.