This apartment is in a fantastic area. It is in walking distance to parks, great shops, restaurants, and bars, and some of Lisbon's other cool attractions. The apartment also has a great balcony, perfect for morning coffee or evening wine. Yet there are a few reasons I would never stay there again.
First, the bathroom, and especially the shower, is tiny. It is, at best, suited for an individual -- but a fairly small one. I could not move in it at all (I would literally bang my arms against the sides as I cleansed). Furthermore, the shower does not drain well. This not only meant that I had to stand in a pool of water while showering (even though I lathered with the water off to prevent the build up), but my partner had to wait upwards of 15 minutes to shower after me.
In addition, the bed is very, very uncomfortable and resulted in a week of terrible sleep. Stated succinctly, the place needs a new mattress and pillows. Worsening the sleep was the fact that the neighbors played very loud music every night, partying into the 3 a.m. hour (which really was worse because the pandemic-induced early bar closure meant that we were typically back in the apartment by 11 p.m.). Moreover, the key to the downstairs door need to be fixed. Claudio (the guy hired to manage the place) acknowledged from the outset that it did not work well and that it would take multiple attempts to open. (He said it was no big deal but, in reality, it often took 5 minutes or so to open the main door while standing next to the building's trash can in front of the entrance, which was overflowing with garbage).
Frankly, some of these things would have gone unsaid if it were not for the host's unprofessionalism. For example, during the walk through, Claudio showed us where the remote was for the AC on the walk through, but oddly never demonstrated how it worked. It turned out that the AC did not work. So, after getting back to the apartment that first night -- when the day's temperature had been over 90° degrees (~32/33°C) -- we tried to use it but it was in vain. When we texted and called Claudio, he said he would come by in the morning to look at it instead of telling us how to fix it. When he came, he fixed it within 5 minutes by removing some contraption that he said the owner put on intentionally to keep people from using the AC. It just seemed deceitful to not tell us this during the walk through or on the phone when he obviously knew what was wrong.
Also, we were given one large towel and one small towel for the entire week that we stayed there. So we had to wash them to have fresh towels. When we texted Claudio about how to operate the washing machine (it only has useless pictures on it instead of words) and asked if it had a dryer function, he said that it should work and that nobody every complained about it before. He then added that he'd forgotten to tell us, but if we wanted another towel it would cost an extra 30 euros. It turns out there was no dryer function on the machine, which again seemed deceitful not to just tell us directly -- or, perhaps, he did not know the details about the place. (This very well could have been the case given that he was confused about which tenants we were when we texted about the apartment.) We then found a clothes drying rack in the apartment, which was fine (but he could have just told us from the start).
Finally, Claudio asked me in person on the first day to let him know if we were going to leave the apartment earlier than our set departure date so that the cleaning crew could come prepare the place for the next people. I told him that I would let him know if that was the case (but we were there for a week before going to Spain). He then texted me the same question when we were just days into our stay (after all of the above issues had transpired), which seemed very odd, tone-deaf, and almost as if he was prodding us to leave early.
Again, the place is in a great neighborhood and has some good features. But the bed, neighbors, bathroom, and host are not among them. I would recommend that you definitely stay in Principe Real, but find another place if you are looking for a more restful stay and a good rapport with the host.