This dish might not be for everyone. I tried it and it was ok for me. If you want to try one in Tokyo area, might as well check Negishi (they have their stores in several locations).
Once you wrap your head around the fact that it's tongue (if you're from a country that doesn't typically eat animal tongue) - it's a tasty treat. We had a bowl of thinly sliced beef tongue at a restaurant near Matsushima.