Using a VPN Service, your computer (or Cell Phone over Wifi) will no longer appear to be connecting to the internet through your ISP (or Wifi hotspots). You can choose which country (which affects your IP range) you choose to appear to be from.
Also, VPNs inherently use SSL, so all communication while connected through the VPN is encrypted. One example I recall reading where this was useful was for reporters who (A) needed a connection outside of the country they were in (like China with their strict internet restrictions), and (B) wanted their communications back to work to be encrypted; keeping their story from being intercepted before it was published.
We like to think that our personal Cell Phones are safe, but when we are use shared WiFi connections, your data can be compromised by others sharing the same Wifi hotspot. Use a VPN on your Cell and keep your communication private/encrypted over WiFi.