It's actually pretty damn good in terms of privacy. It's Mozilla VPN, which is white labelled and resold Mullvad (but at the same price).

Mullvad is a no logs provider with a good track record.

Unfortunately,: https://korben.info/en/mullvad-cofounder-funding-far-right.html

I typically avoid VPN's, becuaee in my opinion DNS over TLS/HTTPs + HTTPS are enough for my privacy/security needs, but I will happily use the free VPN every once in a while to get around a firewall or test if a website is universally down. I find it very useful, and am happy that firefox has added. And although I'm not entirely pleased given recent relevations about Mullvad, I'm happy to see that Mozilla is attempting to make money by offering privacy, rather than taking it away.