How much time is really spent integrating FB Connect?
I haven't looked into the API or what it takes to integrate it, but I assumed (bad habit, I know) it wouldn't necessarily be rocket science. Aren't most API's relatively simple to use compared to the actually building of an app?
Plus, if it causes a huge increase in users and tire-kickers, it seems an app would get more chances to show off their sexy features anyway.
I think the most non-trivial thing would be integrating with the current site sign-on. Issues such as an existing users that decide to sign on with facebook (which is linked to a different e-mail address) could become a problem on the backend.
The problem was we did not test the actual login, just having the option. The client did not give us details on revenue/turnover or hoe many people actually used login of facebook.
It was a health product on the US market.
It depends on your execution.
In general, reducing friction will increase signups. That's hard to argue against. The only situation where reducing friction will reduce signups is where you seemingly reduce perceived value by doing it, but again, that all depends on execution.
Facebook connect sign in could be executed in a couple of ways:
1) Click a Facebook button. Click approve. Boom, you're registered in your app.
2) Click a Facebook button. Click approve. Get redirected to another signup form and have to fill in more data. Click "Send". Oops, there was an error with your form input, please enter a valid email address. Fill in data. Click "Send".
I can say with confidence that (1) will increase signups, but (2) will hardly move the needle.
It depends on your execution.
however, as others have mentioned on HN, by reducing friction you increase the amount of "tyre-kickers" - people who just want to check things out and leave.
that's not such a bad thing if your cost-per-user is negligible, or you have some kind of post-signup campaign in place (e.g. an email after inactivity that tries to "reactivate" the user).
in those situations, the more people you can expose your company to, the better. I'd wager that many startups don't implement Facebook signin because of the engineering overhead that could be spent on sexy new features.