This place was great and one of the highlights of this trip. Of all the themed restaurants I've been to, the ones in Tallinn hit closest to the mark.
By lunchtime, my fellow travellers and I were getting hungry and counting up the confusion of Estonian krona (I believe) in our pockets, wondering if we'd have to settle on reliably cheap McDonald's or if we could check out the local cuisine. We were heading back up towards the entrance to Old Town when we passed a very colourfully medieval section of town. The menu boards outside caught our attention, and it wasn't long before we'd abandoned all thoughts of McDonald's.
The menu was incredible, with things like beaver tail salad and wild boar for a reasonable price. (I believe it worked out to the equivalent of 5 to 7 UK pounds, or about $10, though in reality it might have been a bit cheaper.) The atmosphere inside was more authentic than in any other themed place I've visited, with the waiting staff all in authentic clothing, down to worn leather bags at the waist to carry their order pads. The place was stuccoed inside and completely lit with candles and decorated with heavy wooden tables. It was dark and cool inside, with the smell of well-cooked meats and sweet beers. I could have been in a reenactment.
In the end (in our curiosity to try more than one place), we decided to have a beer and an appetizer in the Peppersack and the main course in a restaurant across the street. We ordered the beaver tail salad and some honeyed beer, which came in big clay tankards and was both refreshing and pleasantly warming. Even if you don't try the food (I can only vouch for the salad, which was indeed nice), I recommend that you pop in for a cheap mug of honey beer. It was a nice place, all in all, and it very pleasantly rounded off the Tallinn experience.