[gav]

It is beautiful and it's a tough problem to solve--the login/signup is a big cause of friction and confusion to users.

I would wonder how many users notice the "Sign Up" link or read it as "Sign In" and not understand how to proceed.

The distinction between username and email is lost on a lot of people, unless you expect accounts to outlive emails and the value of having an account is worth this friction (think Dropbox or online banking) then use an email or phone instead.

I do wonder if for most apps a two-step process is easier: enter your email/phone to continue, if that exists ask them to logon or otherwise create an account. I realize there are concerns about account enumeration, which are valid, but end up being overly hostile to the user (plus most registration flows leak anyway).

[xenospn]

Thats a good idea! I might try that.