My dad got one, just to see if all the hype was true. I'm in charge of nail trimming around here, and I'm not a big fan.
My 2 Labs don't like it. They're not skittish dogs, and are fine with normal nail clippers. They both pulled away, and didn't seem to like the feeling of the grinder on their nails.
For the cats, it just.. sucks to be honest. Maybe I need the smaller version to try, but it just seems to take forever to do one nail when I could've had the entire paw done! So yeah, I'll be sticking with my normal nail clippers!