Migrated from LastPass to Bitwarden about a month ago due to the endless compatibility problems of LP with newer Firefox versions.

I am impressed by the usability and stability of this add-on. It's fast! Migrating a few thousands accounts is done in an instance and error-free. At first the interface seems a bit awkward, but after getting used to it, it turns out to be much more intuitive than comparable add-ons. The developer very carefully listens to the users and quickly responds with smart improvements. Excellent!

Because this is an open source add-on, the base of trust is reasonably acceptable. An independent security audit could promote this add-on to far beyond its competitors. In that case: six stars!

EDIT: I already found some quite encouraging words about Bitwarden at hackerone.com