As others have said, it certainly can contribute to extending the battery between charges since it turns off all Radio Frequency transmitters (i.e. Cellular, 3G, 4G, WIFI, Bluetooth). Once activated, you can then selectively turn on WIFI and/or Bluetooth to have limited connectivity such as to be able to communicate via Skype or other VOIP, as well as to use the Bluetooth features for BT Headsets, keyboards, mice, etc.
It's a quick way to turn off all of the radios at once, but by selectively reactivating those you want active, you can both reduce power consumption and still have full use of the unit depending on what you are doing with it. Also, if you are in an area (such as on a plane, or in a hospital for instance) that has restrictions to Radio Frequency transmitters, you can quickly and effectively "silence" those radios to prevent RF interference from creating problems for sensitive equipment nearby.