It gets better. the most demanded feature -- whitelisting (i.e. when vpn is active and used only with listed sites, which is the most sensible mode in a case when your government breaks the Internet part by part) is absent, though blacklisting was added lately. There was some problems with UI (I needed to relogin sometimes), but overall not bad, get things done.

This add-on was causing me issues very often, like for others. Then I tried disabling all other add-ons and it worked! It's working even all disabled add-ons are re-enabled again so I can't tell what caused this. It may just be some other extension, it may be Firefox glitch or NordVpn extension issue. Until I figure this out it's 4 stars. Otherwise it's 5.

UPDATE January-2022:
No issues since using v2.40.0; it seems faster and I also like the new 'Pause' feature. Giving it 3 more stars.

June-2021:
It got really bad, broken Login! Claims "succesfully connected" to NordVPN in pop up window while exension icon shows it is not. NordVPN suggests to reinstall the extension but that's just a temporary fix; I'm getting tired of re-installing every week or so and perhaps it's time to trash it if NordVPN can't resolve it for good.

EDIT3: What do you know? It seems that NordVPN finally listened to customers.
Since the last update, I have to say that it worked seamlessly. I don't have to re-login everytime or uninstall/reinstall the extension, and NordVPN added 2FA. Increasing temporary my rating to 4, and I will adjust accordingly with time.
I have to acknowledge you did improve NordVPN.

EDIT2: Obviously everybody has issues with your addon so please stop saying "Sorry, if it persists contact the customer support" and fix your lousy login....

EDIT: Nope, even without any other addon and on different systems the login error is there, and completely random. Your login system is just a bad idea IMO. I miss the old one with login and password, and you could just add 2FA. It used to randomly disconnect but it was easier to connect.

Like many people I have this login issue, only workaround is to uninstall/reinstall the addon.
This NordAccount thing is the worst idea ever, login and password was better, I have to constantly relogin through the browser, which defeats the purpose of the VPN when I am in a censored country. Definitely not renewing....

Works ok but you better hope the node you are closest too hasn't been banned by Netflix or Disney+ because you have only the one choice per nation... The desktop app lets you choose between multiple nodes within a nation so it's better.

I have been using it for a while with great confidence. thanks.

The login issue still not fixed. It looks like not just me. It seems like nord doesn't want to fix this broken add-on.
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It works after I reinstall this add-on. Even if it works now, I concern the problem like this happen time to time. I hope your add-on will be stabilized soon.
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There is similar problem like I experienced before happens today. I can log in but after I see the pop up 'you logged in successfully' the add-on still not logged in. I try to log in several times but the add-on keep shows 'log into your account'.
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After I saw your reply and I reinstall this add-on, It works! thx for your fast support.
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after I changed wifi router, it doesn't work. I can't log in this add-on. It says 'something went wrong'. Well, I can log in when I use other vpn however after it says 'You can now close this window', this add-on doesn't work.

Good, our free VPN service.

It's good for those who are already subscribed to the plan. All you have to do is login and you're able to connect right after it. It even supports closing Firefox and re-opening again that means once you turn the vpn on you can restart Firefox as much you like and the vpn will still be active. However, my only complain is it doesn't have much server in or near Australia.