I bought this grinder as a replacement for a no-name box mill. I immediately liked the solid construction, with proper bearings (so the shaft doesn't move much from side to side). I was even more satisfied once I tried grinding some beans -- it grinds quickly, easily, and evenly. When making coffee in a cafetierre, I get significantly less sludge in the bottom of the cup than I did with the old grinder. Similarly, it works well with a vacuum brewer. My only (minor) complaint is that it takes two fills of the top hopper to grind enough beans for my 8 cup pot. It's still fairly quick, though: maybe a minute, at the most, depending on how quickly you crank it.
For a while, I also used it as an espresso grinder. To get a fine enough grind to work well with my Briel Chamonix (after removing the crema disk -- see my review), I had to adjust the mill well past the point where the burrs started to touch. I don't think this actually damages the burrs too much (they're supposed to be tool-grade steel, and in any case they're not moving particularly fast), but it's noisy and the coffee grinds rather slowly. Takes longer to grind for one double espresso than it does for an 8 cup vac-pot. It's also quite hard to keep the grind consistent, particularly if you use a single grinder for both espresso and other forms of coffee. The grind adjustment is infinitely variable (a nut that you can turn with your fingers), and once you get into the espresso range, a very small change can make a big difference to your shots. After a while, I realized that this grinder wasn't really designed with espresso in mind, so my ratings reflect my experiences making other kinds of coffee. That isn't to say I didn't have some very good shots of espresso while using this grinder: sometimes, I got the adjustment spot-on and it worked very well. However, even making marks on the adjustment nut, I rarely managed to get back to the sweet-spot the next time I adjusted it.
I've since got a Rancilio grinder for espresso, which gives a consistent grind in just a few seconds. But I still use the Zassenhaus regularly when making vac-pot or caffetiere coffee, and it performs excellently.