I use because i like my privacy, and this services normaly remove web trakings, stats and hidde your real IP and all the trafic is encrypted between your device and the VPN server. I use with Wifi and with celular data.
Normally is not recomended use public Wifi spot without protect your system.
I use TunnelBear without any problem in two OSX, in a iPod Touch, in a iPad and in a iPhone. (The interface of this app is arggggggggg)
Their paid accounts are for five devices. They have a free account with 500MB/month + 1GB (if you twitter)
For iOS there is a free service: unlimited free vpn by betternet
If you use a VPN you lost part of bandwidth (5%-10% in a good case, more in a poor VPN service), now... you must select the point closed to your location. I am in Basque Country and I use France.
(sorry for my poor english)
