Mixed. Sounds good, but I'm not sure about the safety. And being able to register the 2FA keys with the passwords is, in my opinion, not a good practice (even of course it is easier to use).
As I understand it the app is not opensource either.
The Windows Companion application is difficult to uninstall.
OK mozila puts his "recommended" label, but -excuse me- I ended up not using it anymore out of mistrust.