As others have noted, this is a perfect location for exploring this wonderful North End neighborhood (and beyond) It was remarkably quiet given the tight buildings..and as it's top floor, no footsteps overhead. We are actually from another Boston 'hood', and we're having a ball exploring our own city (highly recommend, wherever you live, getting to know your own back yard in this quirky way)
For folks with physical limitations, yes, it's up 4 narrow, not super clean, flights of stairs...and the building itself is at the end of an alley. We scrounged a bit for sheets and covers...and while sufficiently clean, the place felt a little tired...but truly the location makes up for any short comings. Great cafes, of course, and the nearby Greenway is a delight.