Add-on stopped working for me (blank screen in vault after login) since the latest Firefox update was rolled out. Solution for me was: Re-installing the add-on.

In general I find LastPass very useful and inuitive to use. It saves passwords automatically (or suggests to do so) on webpages and the interface (the vault) seems pretty tidy.

I loved it as a free password manager. Although now that they only support one type of terminal (smartphone OR computer OR sth else) in the free version that love has somewhat faded. But considering that the smartphone app was much heavier and wiggly in its use I'm fine with only using it on my PC and I overall still like it. Seems easy enough to use for people who haven't used a password manager before!