Rated 3 out of 5 stars

I don't know if this is just because I'm using Digital Persona or what, but it's just not doing what I need it to and it's pretty laggy. If I set it to automatically pop up, then it's pretty obtrusive when visiting sites that I don't want to log into that have a login section, as it pops up over my navigation bar every time. If I turn it off, then manually activating it usually results in me sitting for 10-15 seconds waiting on it, which, by that time, I could have already typed in my login information manually 3 times. I really think one thing could fix all this: make it to where there is a small version of the login screen that fingerfox pops up and allow the user to place it on the screen where they want. Currently, it pops up over the navigation buttons at the top left, and that just results in me getting frustrated when trying to get around the web quicker, as I have to close it out/minimize it like every 1 or 2 minutes. You can move it, but the next site you log into puts it right back in the default position. By making a smaller pop-up box and allowing users to move it and leave it where they want it to always be, the auto pop-up feature wouldn't be obtrusive. Just a suggestion that I think would garner you many more 4 and 5 star reviews. Unfortunately, for now, I can't do any better than a 3 (probably more like a 2, but I'll give you the benefit of a doubt that you might implement a change like this). Appreciate your effort to provide a fingerprint reader for firefox 4 though!

This review is for a previous version of the add-on (2.20.1). 

Thank you for providing many details :)
10-15 seconds is too long, shouldn't be that much. But when you have to load an external app each time, it's hard to improve performance. You could try enabling "start with windows", as it should decrease the delay.
You should not select "real automatic popup", but instead, select automatic popup in the login window for the sites where you actually want it to popup automatically.
I will still consider your suggestions though - making the window smaller by default, and making it possible to change the default location.