Easy and quick to reload and half the price of 38s to shoot. For someone that enjoys revolvers it is a Win/Win. And, it allows for Ammo consolidation.
Still, there is NOTHING wrong with a S&W Model 625 or older flavor, and anyone with 1911s would be remiss without a revolver in .45 ACP. Additionally, no collection would be complete without at least one variety of .357 double-action revolver. But, a 9mm is quite sweet!
"That's a nice plastic fantastic, but I got a wheel gun!" - Elmer Fudd
That would be pretty cool and good enough for combat accuracy, however, the 9mm accuracy would suffer slightly, just as with the Ruger Blackhawk dual cylinder version.