Yes, the stairs are a bit intense, but that's the only negative to this location. This shouldn't be a deterrent to stay here, because the amenities, size and proximity to several great sights outweigh a little end-of-day cardio.
Space was great and the beds were comfortable. 2 couples and 2 singles could easily sleep here without any issues, not only with sleep area, but with space in general. The apartment is huge.
There's lighting everywhere, tons of extra hangers, a really nice stereo, courtesy umbrellas and Massimiliano was gracious enough to hold out luggage while we explored a bit more before leaving to Venice. Major burden relief.
This location is less than 12-min walking time to several major tourist spots. Not to mention all the eateries, bars and shops. Very safe area and lot of locals wondering around which was nice to see. Had a great time.