An interesting aspect to the story is the singing accompaniment all the way through. Lynda Baron sings a version of the "Ballad of the Last Chance Saloon" tailoring the stanzas to the events on-screen. It is a catchy song and adds an interesting counterpoint.
Generally I think this story has very little interest or value. It's not as bad as the preceeding Toymaker story, but still not terribly good nor interesting. There weren't any questions I perceived, no theme, just some people being tossed aimlessly through an event in history.
What's the point of having the Doctor visit these episodes in history and essentially do nothing other than ride the stream of events? In this story we see the Doctor and crew as rather ineffectual agents, they don't initiate any actions, etc. Well, with one exception in that Dodo managed to beat Doc Holliday to the draw and force him to take her back to Tombstone.