Yeah, I switched to them after mullvad (i I also tried airvpn before Proton) and it works great.
One extremely annoying thing with Proton VPN is that the port changes after every single (re)connection so you need to reconfigure your torrent client.
Fortunately there is a fork of the VPN client I use which automatically configures qbittorrent with the new port.
On linux there’s a bash script for port forwarding, and if you execute it right after reboot (preferably via cron) it’ll be the same port as before reboot.