To add to every other positive review on here, these are indeed the best sandwiches I have ever eaten, and I thank Trip Advisor for alerting me to it.
Myself and my partner went there during our tour of Italy in August 2012. The first time we went, there was a very long queue, but we persevered and were glad we did! We asked for the person serving us to give us what he thought would be nice, and had two different sandwiches which we shared. One had some sort of soft cheese and salami style meat (not sure what it was exactly) and was one of the best things I have ever eaten! The other sandwich was also gorgeous.
It was so good that we went back earlier the next day before a trip to Pisa, when the queue was much smaller. We ate the sandwiches in the shade of the leaning tower. Bliss!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.