Fred99:

I've used a Mazzer Mini for 10 years.  AFAIK the only design change since the 1960s is that you've been able to get them in a couple of colours other than silver or black.
Still on original burrs. (probably due for replacement based on kg of coffee that's been ground, but it's still working perfectly, so I won't bother until it doesn't - note to never buy replacement burrs on line "cheap" - they will be fakes).  It's a vastly over-engineered mass of metal with an underworked motor running so slow that the grind remains constant whether you're making one cup or ten (the burrs and motor etc don't get hot), comes with a lifetime warranty for commercial use, contains no electronic wizardry, and seems to be the standard for use in cafes (they mainly use larger Mazzers, but they'll often have a mini on the bench to use for decaf or single origin, special blends etc).  I very seldom need to change the grind setting, but if a tweak is needed, then usually get it spot on with one tweak.  Maybe that's just familiarity after using it so long, maybe more that when I started making home espresso I used to read forums where people claimed that everything from small humidity changes or time of day or age of beans made big differences.  I think it's partly because some of their fancy electronic grinders really aren't as good as they're made out to be.

Good points mentioned above.  Bad points - they're kind of slow, maybe 20 seconds to grind a double shot, they have a doser which needs cleaning out (upside to a doser is that thwacking the grounds breaks up clumping), and that without electronics, servos etc, it would be inconvenient to use where the grind had to be adjusted to suit different brew methods, ie if you needed to change from espresso to french press, or if you wanted to change settings frequently to use different beans, you'd probably have to mark the adjuster ring with a felt pen or something unless you've got a very good memory.