Felipe’s place is ok for us, but not a good value as I paid quite a bit in peak times.
The apartment is situated in the heart of Barrio Alto. Indeed as described, you will need to climb flights of stairs to get to the place. Do not underestimate this like I did - first you need to climb about 5 floors up to get to the entrance street, then another 3 floors up to get to the apartment. If you have large luggage I strongly advise you to think again.
It’s a historic/old house and as such the condition is a bit worse than I expected - uneven floors, low ceiling. If you like the experience, go for it. Not really for me though coming from North America. But I would say the place is clean.
In terms of noise, I arrived in the midst of the Lisbon festival, so party and barbecue on the street until 2am. Not a problem for me, but just so you all be aware.