Pros: Claw points are ground down quickly, cats may show less nervousness around it than around clippers.
Cons: Might grind too far while first getting used to it. Costs more than many clippers. Low humming sound might bother sensitive cats.
This is supposed to be less traumatic on nervous cats than clipping their claws and my experience bears that out. Both Chula and Paul hung around afterward to check it out, instead of bolting for the next room like they usually do after a session with the clippers. It makes a low humming sound as it grinds that might bother some cats, but neither of mine seemed to notice it at all.
While I am still getting used to the grinder, I have only taken off the actual sharp points. They do come off quickly so I've not yet tried grinding higher up yet.
There is a disconcerting smell of burning claw that accompanies the grinding but neither Paul nor Chula showed any discomfort whatsoever.
It probably takes less time to clip claws than to grind them down, so that is a point to consider when holding a squirming cat. However, I think it would be easier to make a mistake and clip the claw up at the quick than it would be to grind too far with this device.
If you already have a good routine down with the clippers, there isn't any need to pay the extra money for a nail grinder. If clipping time is a nightmare with your cat scratching and fighting, this isn't going to make things that much easier, although if you goof, you won't cut off the nail to the quick. If your cats are like mine, where they put up with it grudgingly for a couple of claws at a time, the grinder really works well.