The Rhino seems a lot like many other out there designs that are mechanically fantastic: but wholly unnecessary.
In technical terms: the exceptionally low center of bore in relation to the hand gives added recoil control and therefore faster follow up shots.
Then again; if rapid fire is your absolute goal - get an auto loader. Even if you don't like auto loaders or you want to champion the argument that revolvers are supremely reliable by comparison, you raise a whole other issue.
Lets say the argument is reliability of a revolver, ok.
Single actions are slow to load and or fire. ok.
Double actions with a star extractor, much faster reloading and firing. ok.
Bore axis in relation to hand is too high - makes accurate follow up shots slower. ok.
Rhino: bore axis is within the palm, extremely rapid accurate fire. ok.
Now I can unload all 6 shots as fast as an auto loader. ok.
Speed loaders every 6 rounds still slower than a 1911 8 round stick magazine....
Rhino seems to follow an evolutionary dead end. If I'm carrying a revolver for reliability than I'm not necessary concerned with firing as fast as humanly possible: because i only have 6 rounds before I have to reload. Now if recoil control in terms of making the firearm more pleasant to shoot is the point of it: I'm cool with that - but it's still only .357 magnum. When they make the Rhino in .454 casull (and up) and the bore axis in the palm makes it comfortable to shoot: give me a call.
The Rhino really looks like a solution in search of a problem. Not entirely unlike the Webley-Fosbery Self-Cocking Automatic Revolver or the Mateba. The Mateba has almost the same bore axis position by the way - just for future references. My only revolver, btw, is a Ruger Super blackhawk. It loads and shoots slow, but it's a .44 mag - I don't really have to rush.
Don't get me wrong: Rhino is an eat gun, I'd rather have it in a heavier caliber and without the built in rails that are designed to make it look cool. But hey: that's just preference.