An OS is not outdated unless none of the software and hardware supports it. You can say iOS 1-4 is outdated, but iOS 5 and iOS 6 is hardly outdated.
Well if you really wanted to get technical then no version of iOS is outdated unless it is no longer used by anyone. What I simply meant was that running up-to-date software provides feature and security enhancements and that the older software is left to go stale.