So far,our testers love it. It seems to have gotten them quickly past the user dread. It also means your first participation in our site can happen by submitting one form and confirming one email. That's somewhere between two and five steps shorter than had we required account setup. While it adds an extra step to subsequent interaction, email confirmation, we feel like it's a good trade off for them. After all, going through a password reset when you come back to the site is an easy way to lose people.
And for us, it eliminated a lot of development headaches. When a user first participates in the site we assign them a randomly generated username. And they can change it to whatever they like ... They just fill put the change my username form and confirm by email.
Obviously, if we wanted to save credit card info or something like that we might need to modify this approach for PCI compliance, but I believe a fundamentally similar workflow could be employed even then.