It is a really nice commercial grade flat burr grinder that one can enjoy in the home too (if you can afford it and have space for it).
Positive Product Points
Fast Quiet Easy Fluffy grinds directly into your PF Well constructed Easy to work on
Negative Product Points
Big footprint and hopper for home use Expensive for home use Not sure the advantage of the ES (stepped version)
Detailed Commentary
Eric Bice's review is very good, so I will just add a few notes.
1) I agree the grind quality and coffee this machine produces are excellent. The dosing (time) is very easy to dial in. The grounds are fluffy, and require no WDT. Just level and go. I am not even sure you need to level.
2) I also agree with Eric, the clumping issue seems a little overblown, especially for home use. That said, the taping open of the chute mod as Eric described on the older style of grind chamber did not work for me. What worked well was the new grind chamber design. This really made a surprisingly big difference on my machine eliminating virtually all clumps and kept my countertop significantly cleaner. Also, if you ever need to open the burr chamber for any reason (replace burrs, stone), there is no cross-theading risk. Three simple screws are used. Nice design.
3) I also have the ES. I feel Eric is right, the steps are small. But why not make them all Vario? The adjustment is simple and infinite.
4) It is big. I have a Duetto2 which is a big machine for a home countertop. They look nice together, but you will definitely need space. I chopped my hopper that came with it to fit my grinder under my kitchen cabinets. I use less coffee beans in the hopper (to preserve freshness) anyway. I think its size is partly to be a stable base for the commercial 3lb hopper. I believe this large base/enclosure helps it be a bit quieter and cooler by design too.
5) It is a beautiful simple Swiss/German industrial design that is well constructed and easy to work on. Support from Mahlkonig USA has been great so far. I have been able to get new burrs and upgrade my grind chamber (although not cheap), making my used grinder perform just like new. It should have an easy rest of its life in my single family home.
6) It is much quieter than what I am used to. With my new rotary pump espresso machine and this grinder, the family conversation does not have to stop while I am making espresso drinks. This plus its efficiency means I get to return to the table and eat sooner.
Buying Experience
I bought mine used locally from a coffee shop that went out of business. In retrospect, I paid way too much. I felt bad trying to haggle with a guy who lost his business surrounded by the remains of his equipment in his garage. No tax or shipping, I guess. It is a big ticket purchase and I suggest you should take no chances like I did. I love my grinder now, but had to upgrade the burrs and grind chamber to get new/excellent performance. The best way to go IMHO is new with a great vendor (eg. Chris Coffee) or contact Mahlkonig USA and try to get a scratch/dent/demo. The savings are significant and you will be backed by support.
Three Month Followup
Works exactly as stated. I have experimented with many espresso blends now. The steps are small enough, that I have had no problems at all. I still recommend the Vario, as there is no advantage of a stepped grinder that I can think of. I am very happy with this grinder.