The Underground Butcher is part of the Underground Food Collective here in town. I love pretty much everything that Underground Food Collective does.
The Underground Butcher is great. It has very high quality products from (mostly) local vendors. Their cheese selection is incredible and they will patiently let you sample several in the search of the perfect pairing (I know from experience). Their selection of meats are not for the faint of heart. You will find entire pig heads here.
I haven't yet tried their sandwiches, but would like to.
The only reason I can't give it 5 stars is twofold. The prices on some of their items are quite high. Also, I recently bought some delicious looking sausage here, went straight home and cooked them, but they came out bone dry. It was really disappointing, but I do think it could be partially my fault, as I might have cooked them too long.