The minisodes do what they need too

A little bit of added colour which doesn’t outstay its welcome and makes you curious about The Gunslinger.

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.