Very consistent grind. Plenty of weight and power.

On/off switch is spring toggled. A few beans always get caught in the screw wells of the bean deflector.

If you are a vacpot coffee enthusiast, as I am, then the Rancilio is a "must have" grinder. A vacpot is at its best when the glass filter rod is used - more flavor constituents get through to the final cup, and there is none of the hassle of maintaining cloth filters or having to fabricate new ones out of old T-shirts for your 70 year old Silex  when the old original filters are not showing up on Ebay.  One hears some griping about filter rods and "stalled" draw downs in vacpots, but the culprit is nearly always the bean grinder. Even the very decent Solis Maestro grinder will pretty quickly get dull enough from daily usage to output a significant fraction of overly fine powder, and that is what clogs filter rods. The Rancilio emits such a uniform grind that a near espresso fineness will still permit a smooth and timely pull down in the vacpot. The brew is darkly translucent, rich with oils and nanosolids but with no mud or haze.  
Another consideration is that more uniformly ground coffee yields a better extraction no matter what the brewing process.  If particle size is all over the map from talc to big stuff then there will always be some fraction of the coffee that is over-extracted and some fraction that is under- extracted, and it doesn't take much of this inexactitude to sully our precious elixir causing thereby our noses to wrinkle ever so slightly and starting us off on the wrong foot for the day.   Not an issue with the Rancilio!  I suspect as well that plunge pot coffee drinkers would find their brew less "chewy"  if they graduated to a grinder of this caliber too. They could more accurately fine tune the grind to the filter mesh openings and get cleaner and more consistently extracted coffee. However, I'm not going to experiment with this because if I discovered that a Rancilio and a plunge pot made wonderful, clear coffee then it would make my unruly collection of vacpots seem impertinent.
The negatives are minor. The spring loaded on/off switch must be held down to grind. You can't walk away from it when grinding. However, this may make sense after all. Sometimes a rock will sneak its way into a batch of coffee (yumping Yemeni!) and if you're right there riding the switch then you may be able to cut the power quickly enough to avoid seriously damaging the grinding burrs. As for the bean deflector screw wells trapping a few beans, it's no problem just to unscrew the deflector and do away with it.

Sweet Maria's is where I buy my beans and most of my accessories. Never had any problem at all with these people.