Rated 4 out of 5 stars

This addon is absolutely necessary due to Firefox's extremely annoying master password UI. Every time I start Firefox, Sync steals focus and fires a modal master password prompt without even telling why, and this is by design! Master Password+ gets rid of them. Not 5 stars because it doesn't work well with Secure Login (need to reload page) and because the "Lock" hotkeys cannot be disabled.

This review is for a previous version of the add-on (1.16.1). 

The hotkeys can be disabled by removing them (focus on the field and press a single key)