[MatthewPhillips]

Implement Facebook Connect: 5 minutes. Implement own login system (with login screen, register screen, forgot your password screen, CAPTCHA, and making sure BCrypt is working properly): X hours. I'll do the former, even if it annoys 0.1% of possible users.

[moheeb]

I have to add that your method makes it really easy to avoid lame sites also!

[chico_dusty]

Implement Facebook Connect: 5 minutes

Implement own login system: X hours

Selling your users privacy down the river: Priceless