I am a huge fan of calendar subscriptions. It is so much better to subscribe to something that to import it, so that the maintainer can make changes and have then automatically reflect on everyone else's calendars. Many of us have multiple iPhone, iPad, OSX devices though and would like to see the subscriptions reflected in multiple places. So note the following:
If you subscribe to a calendar using your IOS device, the subscription only appears on that device and you need to subscribe on each device.
However, if you use the Calendar application in OSX to subscribe to your calendar, you have the option to add the subscription to iCloud, which in turns adds it to all devices that are syncing Calendars with your iCloud account automatically. This is a much better solution.
Unfortunately, if you don't have OSX you are out of luck. The browser based iCloud access does not allow subscriptions to be added, and you cannot add a subscription to iCloud through a mobile Calendar app, so this really only works for Mac users.