Email as Username

Like most 'professional' and customer-friendly websites, you only has to enter your email address to log in, not remember a username (and even choosing a username is quite tricky sometimes).

I think it is vitally important to keep things simple for customers/members. Many customers have cancelled their order as soon as they get frustrated with the payment process.

Do it like amazon at least: you type in your email address and password and that's it.

Yes I know joomla has this complicated username system and that's probably why so few good commercial sites use joomla as their back end - or if they do, they lose a lot of sales because of it.

Keep it simple: just a unique email address for the username and allow the user to choose his/her own password, which can modified or sent as reminder later.