I hate coffee grinders.
They are loud, they are messy, they don't adjust right, and they don't measure out the coffee accurately. If you buy one expecting something like a grinder in the supermarket, that will do one pound of coffee, silently, mess free, in 15 seconds, and all for free, think again. Unfortunately, ground coffee goes stale in a few hours, so one needs a grinder. First you get a burr grinder for $60 to $80, it sounds like an air raid siren, it sprays staticy coffee like a technology museum exhibit gone amok, and there's no click that works right for your espresso machine. And so the process of disillusionment begins. After a while, you'll be writing rave reviews about coffee grinders that make a good repeatable espresso, no matter how awful everything else about them is.
In a perfect world, there would be nothing remarkable about the Mazzer Mini. All it does is grind coffee to the right size. But after the disillusionment, it's a miracle for all the things it doesn't do. It doesn't make a noise; it doesn't make a staticy mess; it dispenses almost all the coffee it grinds; and it doesn't produce a mixture of chunks and dust. All it does is grind coffee for espresso. After you've gotten experienced with other home grinders, you'll realize just how wonderful this is.
I don't hate the Mini.
TECHNICAL DETAILS: The other reviews, including Mark's forthcoming detailed one and his use of the Mazzer as a benchmark in the detailed Innova review gives almost all the details I've gleaned. So I'll confine myself to three short points:
Espresso Quality: Marks rating in the Innova review reflects my experience. The Mazzer produces fines at about the same miniscule rate as the Innova conical, and produces a shot that is as good or slightly better. The ground coffee itself is easier to handle, since it's less fluffy than a the conical's output. No other grinder I've used, admittedly not a stellar bunch, comes close.
Usability of the Grind Adjustment: The adjustment is stepless, but works via a pressure fitting rather than a micrometer adjustment like the Innova. This means that the grind cannot be adjusted as ultra precisely as the Innova's. However, it is much easier to re-adjust the grind for changing weather conditions, or different coffees. It is also adjustable well enough that one gets an extraction within a few seconds of one's target. In sum, I slightly prefer this system to the micro-meter one.
"Bean Dancers:" This is an alt.coffee colloquialism for those who leave the hopper empty, and only put one dose of beans in at a time, in order to get an accurate dose. Not all grinders are suitable for this type of use, since the beans may not feed through properly. I use this method when making coffee for myself alone. The Mazzer is extremely suitable for this type of use. Take the hopper off, put the dose into the grinders throat, seal it with a cup (hint: a 58mm blind filter works perfectly and matches the decor). The grind time is raised from about 12 seconds to about 15, and a bean or two will lodge in the throat and need to be swept in with a brush. However, all the grinds except for about 2 grams will dispense through the doser. So I find this grinder easier to use in this manner than doserless grinders that require extensive chute clearing after every grind. Best of all, when company comes, one can put on the hopper, run 3 to 4 doubles worth into the doser, and play professional barista, rather than standing around waiting for the PF to fill. I should note that many, including Mark, believe bean dancing detracts from the quality of grind, since some of the dancing beans get chipped prior to grinding. This is certainly true; but on the Mazzer, the difference is so small that I can't taste it. It may also mean I'll have to replace the burrs every five years, rather than ten. The benefit is that the dosing is waste free compared to the finger swipe method.