A browser that requires an account to use? No thanks.
The "why do i need an account" popup doesn't properly explain it to me either, syncing should be optional - let me use, or at least try, it without an account first.
Why? Of course so they can have their "registered users" count as high as possible to get another round of VC funding, so that they can drag this thing all the way to the IPO and get a nice and fat exit :)