If the San Callisto hadn't been so packed, I probably wouldn't have paid attention to this pub.
During the one night that we were in Trastevere, Esther, Hubi, and I couldn't find a place at the San Callisto and looked around the piazza to find another refuge.
A banner for Belgian beer Stella Artois caught my eyes... We went in. What a difference from bustling San Callisto! I must say that I didn't even know about the Lord of the Rings at the time (I am now addicted to it), and I don't remember anything that was particular to the book here, but after reading about it, the pub decided to play on the theme full blast and brings devotees of the Tolkien saga when they visit Rome.
This pub is small and narrow but cozy, with an arch and a second room. Music was playing (fortunately not too loud) in the background, and there was a benediction for me: Belgian beers are available (I heard they extended their selection)!
There is also a pub-fare menu available (I never tried it, so I can't say).
What struck us the most was that the staff was all female, and for some reasons, they seemed to be in a competition about who was wearing the shortest skirt. It became kind of a running joke for us, as we would go have a drink there just to see if they kept at it... and they did! But the waitresses were all very friendly.
In short, it is a nice place for the Fellowship fans, beer amateurs, and those who want to take some time off from bustling Trastevere.