I use Linux Mint, currently v.20.3. The Installation instructions for NordVPN on Linux are terrible, and that is being generous. You are told to download the VPN Debian app, which did not work! it installed but would not launch. Next I tried launching NordVPN form the terminal. It worked after a fashion. The issue here was that there is no visual representation of the status of the connection, which I had to keep checking and found it had frequently dropped. I eventually found how to connect via the network manager at the bottom of one of the pages of instructions. That worked (at last!!). Then the next day I stumbled across how to add the NordVPN extension to Firefox and Chrome based browsers on yet another page of instructions. That gave me a visual in the browser of the VPN status.
Honestly, It was a unbelievable faff that took almost 2 days of swearing and reinstalling.

Nord you seriously need to organize your Linux instructions far better than they are at the moment.

My biggest gripe with Nord is that the customer support chat client is absolute garbage. Once you are past the bot and directed to a customer service rep the wait is totally unacceptable. I waited 3 times for over and hour and still got no response from a human.
For Linux users and those that may need customer services Nord is not the best, by a long way.
Once all is installed (eventually) most things seem to work well, especially the browser extension connections.
But there is a caveat to this, use a speed checker on each server. I have found that some servers are running at less than half the speed of others, though allowing Nord to connect to its selected server in any country usually results in a good fast connection.
This may seem like a lot of moaning, but this is a paid service that is actively courting Linux users, so the need to get their act together regarding documentation (or simplify the installation and the customer service bot.)
Now that I have everything sorted I prefer Nord to my previous VPN. I have knocked off one star because of the nightmare installation process for Linux users.