Thanks for the feedback aaronbrethorst. We just rolled out the public beta - https://twitter.com/prateekdayal/status/338902263802236928 and a friend enthusiastically posted this to HN. We are still working on the pricing but there will be a free tier.
We would love for you to try it out (we ask for read permission from Twitter). If you signup and send me an email saying you signed up from HN, I will put you on a free three month account. Thanks
What I mean is that I think you're going to see a significant drop-off in signups by having the Twitter button there in lieu of a standard email/password form. I'd recommend having users link their Twitter account later on.
We would love for you to try it out (we ask for read permission from Twitter). If you signup and send me an email saying you signed up from HN, I will put you on a free three month account. Thanks