First, it is NOT a VPN, it is just a proxy. It is an important difference - it breaks some sites, and some sites that don't want to allow proxy connections won't work. If you want a real security and real reliability - you have to use a system-wide VPN (split tunneling feature don't work).

Second, It is rather buggy and lacks in features. Support is utterly useless! The only response you'll get is "sorry, we can't fix it." I've already tried to resolve issues listed here.

After some time, connection becomes permanent, and attempts to disconnect or change proxy are ignored (you'll see it disconnecting/reconnecting in UI but the actual IP won't change until you restart Firefox). Bypass proxy list is extremely inconvenient to use. You need to reconnect after changing the list (and reconnect is broken), and for some sites it does not work. Also, format is unclear.

And if you want to buy a subscription - wait for sales, prices are quite high, but they regularly drop them massively (sometimes it is a 90% sale).