This add on has saved my ass many times. I have another password manager which is much harder to use, so this is my default. As far as I know you can't download your pw list, otherwise this is a great app!
This review is for a previous version of the add-on (3.7.2).
check out the new backup / restore buttons! It is wise to make a separate backup of key3.db as well as the passwords are encrypted. If you want to store the passwords in plain text (not recommended) you simply hold down SHIFT while hitting the backup button. There is an in depth explanation here: http://quickpasswords.mozdev.org/version.html#3.7.2
Also note that QuickPasswords is building functionality on the (built-in) password management system in Firefox - which also includes SYNC. This means you can load your passwords anywhere on another Firefox version (e.g. on a tablet or mobile device) as long as you log into your firefox account - even without having QuickPasswords.