AirPlay on Apple TV 2 failing more often than it works
No - that is not at all common.

Something is certainly causing the instability so you might need to isolate the potential causes one at a time.


network issues (the most likely culprit but by far not the only one)
Apple TV needing a restore or perhaps just a reboot.
iOS device needing the same (restore or reboot).


Before restoring your iOS device, you might try the other steps first or also you could take your device to another network / Apple TV such as a retail store to test and make sure that's not the cause.