After going to Black Forest Mill, I've tried out a total of four German restaurants with the others being in San Francisco and San Diego. I'm not a German food expert but I have a nice variety to make some comparisons and Black Forest Mill was by far my least favorite or had a notch below in quality to what I've tried.
The beers were very good and were really rock solid. I can imagine many people just coming for the drinks while listening to the music during the lively evenings. I had the Rheinischer Sauerbraten which is a prime sirloin marinated in wine and vinegar for 10 days. The tenderness of the sirloin was great and you could certainly tell that they've marinated it for a considerable amount of time. The downfall was that they added an absurd amount of sweet & sour raisin sauce on top and it almost felt like there was just as much sauce as there was meat on the platter.
The apple red cabbage was a nice tangy sweet flavor but the spaetzle was dull and seemed like they took frozen spaetzle and just reboiled it up quickly and slopped it on the platter. Black Forest Mill had a lot of hit and miss German food experiences. If I had to go again, I would certainly try their schitzel because they had like almost 10 varieties. They were voted "Best of Phoenix German Food" in 2007 and 2008. But looks like 2009 or 2010 wasn't in the cards.