Very good, easy to use, does what you'd expect it to.

works perfectly

Proton Pass is great for using passwords across multiple web services unlike another service I use regularly that limits me to one type of hardware and one account. Love Proton Pass.

Far from perfect. It is not very consistent, sometimes it fails to capture the username, sometimes the password in quite a few websites: about 1 in 10 websites has some kind of problem, my bank (piraeusbank.gr), my Camscanner login (v4.camscanner .com) and politico.eu login page, among others. In the case of politico.eu, the login would completely fail: I couldn't login at all unless I uninstalled the add-on. I have reported these pages, but nothing happened.

I installed Proton Pass because I wasn't happy with Firefox's default password manager either, but since it isn't perfect, I don't see what the advantage is over the (also not perfect) Firefox default password manager: all that changes is which websites don't work. I suspect my problems are Kubuntu Firefox-specific, but the result doesn't change. I'll return to Firefox default password manager for now

I used to use Vaultwarden (a fork of Bitwarden's open source, self-hosted password manager - I do recommend it!) but decided to use Proton's solution since I have moved over to their ecosystem for everything else. I've used LastPass years ago and the comparison to Proton Pass isn't even fair; Proton really has nailed the UI, experience, and details of Pass. Unless LastPass has really changed things, their system is a combination of their old interface and new interface with some features seemingly half-complete. Plus they've lost my trust. Proton on the other hand seems to have a much better architecture for the security of accounts as well as extra layers of safe-guards that can be added if desired.

I highly recommend Proton Pass to everyone!