Mike Resnick pens a fun little tale, re-imagining the shootout at the O.K. Corral in a Weird West/steampunk universe. The Earp brothers don lightweight brass armor and wield Gatling pistols, facing off against the Cowboys. Also, the Thing That Was Johnny Ringo, now an undead gunslinger animated by native shaman Hook Nose to kill Thomas Edison. There's a lot more too it than that, but the combination of weird western steampunk should whet some readers' appetites.
The book flows along in a breezy manner, with a lot of wit and a lot of great setting elements. If I had to nitpick, there's a strange fascinating with the mechanical prostitutes Ned Buntline constructs and maintains, which was a bit much. Other than that, an enjoyably pulpy novel. Buntline is one of those books that's got a lot of great elements, and could have used those parts better, ending up not quite the nerdgasm I expected -- most of the AWESOME!! parts are just window-dressing, like the literal "Bat" Masterson. If it had spent a little more time developing those setting elements or detailing the characters, it would have been a knockout.
It's not the deepest thing I've ever read, but it sure was fun, a pleasant way to spend a few nights. Just don't overthink it.