I generally like Mozilla and their products and I think there's nothing wrong with their VPN.
But the things they say to attract customers are ridiculous!
1. It lets you set your location to another country and buy products available to local shoppers.
Ridiculous because if a store from another country prevents you from buying, it means they will not ship to you. So what if you can trick them to pay if they won't ship it to you?
2. It prevents surcharging based on where you live.
That is because it will pretend you are located elsewhere. So what if that elsewhere is in an even more surchargeable area? You'll pay even more.
3. It protects your credit card info on public wifi.
I think all sites that take credit cards (or that you should use for payments) are already encrypted. "https" says so and as long as you're only logging into the right https sites you should be fine.
Now don't get me wrong: there are other good reasons to use a VPN and I don't know anything about Mozilla's. It's just that I think it's wrong to use these tactics to attract customers.
Become truthful Mozilla!