Solid from everything I've looked over. Their issue previously was logging IP addresses and complying with legal requests. This changed a bit with Swiss legal victories, and the VPN obviously which can be paid in BTC, so there's nothing to log but the address you used to pay, which they don't have a legal requirement to save, but is obviously permanent given blockchain properties. Rumors of LN integration are floating around, which would be quite powerful with the static route where your @proton.me address is also your Ln address. I wrote about them recently:
#228463

You don't need to rely on Proton to have an open source encrypted email.

Simply install open key chain. This works with K-9 Mail and Fair Email, so you end up with end-to-end encryption in your email if you want to. It also works with many other apps, not just email. And of course all this works on GrapheneOS.

So far i'm very happy with it.

Missing some features like a drive client for Linux but everything else is pretty solid.
Would recommend