It does function and allows cross platform interoperability with mobile and other PCs. That said, the Firefox extension seems to have been largely left to rot. The extension logs out constantly and requires re-entering the master password a dozen times a day. Firefox Lastpass is also missing features available in other browsers. There also seem to be more and more logins that Lastpass fails to autofill for all the time and has a bad tendency to want to create redundant site entries.

On the plus side, Lastpass under Firefox is more responsive than the Edge extension