The most horrible experience I ever had with a FireFox addon.

In Jira it will add a string "chromechrome" to the end of my comments - all the time. Only after disabling this extensions are those strings gone in my Jira comments.

The Addon does _not_ save any state, so each time you click the addon (like after copying + pasting your username, you click again to get the password, you will have to search the entry again...).
It is very slow and very buggy.