BB Lisbon is located in a great spot. You'll definitely get the perks of living in Alfama. It's also right next to (literally just 1 door over) to a great vegan Italian place, Horacio. The main benefit of staying here is that you can walk to pretty much anything. You're a 20 min walk from some of the main things to do in Lisbon and its downtown and within walking distance of plenty of cafes, stores, shops, and sights. Getting there the first time can be a bit tricky , I recommend using Google Maps ahead of time and checking the cross streets. Outside of that Bruno's place offers great value and is worth checking out.
The other thing worth noting is that there are many stairs to get to the AirBnB. There are also many stairs within the building if you are located on the upper floors. Most people won't have any issues but if you have trouble with knee pain or climbing lot of stairs, just something to keep in mind.