The flat is really unique and interesting, and the location is very central. However, it is also extremely loud. The windows are very old, and the street outside has 24/7 commotion. The sounds of tourism during the day (bagpipes, tour groups, laughter) are not too bothersome. At night it's another story: people laughing, shouting, fighting, screaming right outside. The nightly bottle pickup at the pubs downstairs sounds like an explosion of glass - and there are all sorts of construction sounds as the city sets up and takes down barriers and event scaffolding.
There are other rentals in the building, and the other owners seem to give little heed to who is in them. Our first night there was a large group partying in their flat and in the halls. After that, we just heard smaller groups of people loudly and drunkenly coming up the steps every night. For some people, this is probably fine. Just be aware that you're putting yourself in party central.
Lastly, I found the pictures to be a bit misleading. The bedroom and common area are the same space, and besides that there's a kitchen with small table, and a bathroom - all of which are attached to a long hallway.