At only two minutes, this really is just the prequel short to The Gunslinger, and nothing more.  While I love that episode, this prequel doesn't have any of the cool visuals I associate with the Eleventh Doctor's gorgeous Old West adventure.  It wasn't unpleasant to watch but added nothing to the original episode and didn't leave me excited about it, either.  There's a lot more fun to be had even when comparing this to other prequels.