We used to advise people to do banking and other important business over their cellular connection when using a mobile device, since it is generally safer than connecting with a public Wi-Fi network. But even that isn't always a safe bet. Researchers have demonstrated how a portable cell tower, such as a femtocell, can be used for malicious ends. The attack hinges on jamming the LTE and 3G bands, which are secured with strong encryption, and forcing devices to connect with a phony tower over the less-secure 2G band. Because the attacker controls the fake tower, he can carry out a man-in-the-middle attack and see all the data passing over the cellular connection. Admittedly, this is an exotic attack, but it's far from impossible.
They even offer the most generous simultaneous connection count, with six simultaneous connections through their network, where everyone else offers five or fewer. NordVPN's network isn't as large as some of their competitors, so if you're trying to obfuscate your tracks, you might want a company with more servers. Otherwise, this company is clearly providing a winning offering.