Counterpoint since I only see anti-FB replies below: I absolutely love seeing OAuth login. I don't have to create yet another password, or worry about whether your site has reasonable password security. Even when I choose to create a login instead, just seeing it gives me some confidence that you're competent enough to set it up, and probably gave some thought to the security trade-offs surrounding login in general.
Have you tried using a password manager? There's no need to worry about a site having reasonable password security when every site has its own unique 15-20 character password that you don't need to know.
