What is the purpose of iPhone VPN?

How can iPhone VPN benefit me? If I could not access a website using a company Wi-Fi, surely I can just switch the Wi-Fi off and use 3g?

VPN could be used for accessing company web applications, email, etc.
I use VPN on my ipad for remoting into my work network to manage virtual machines.

Simply put, an iPhone VPN protects your privacy. When you have a VPN for your smartphone, you have access to four primary advantages over standard internet browsing:

Stop ISP Inspections. Prevent your internet service provider from throttling, prioritizing, and inspecting the data that goes in and out of your iPhone.

Protect the Activities That You Do Online. A VPN is a secure "tunnel" that takes you to the internet. With a VPN, you get to cruise the internet your way, not someone else's way.

Protect Your IP Address. With an iPhone VPN, the only thing websites will see is the server's communications.

Prevent Location Identification. With a VPN, your IP address is substituted for one that is not based on your location. This prevents location-based ads from affecting your internet experience.

VPN service secures your connection and protects your privacy. It can also unblock web sites blocked by your local network. Ignore the spammers above who are tag teaming the answer. Best VPN review sites are total scams and they best reviewed companies are the ones that pay the most kickback to the site owner. Kelly and Harris above are habitual spammers for these fraudulent review sites.

I'd suggest a Personal VPN service http://www.surfbouncer.com