César's place is very well located. It is bright and the right size for one, two/3 people and maybe a child.
It is close to public transport ( tram, buses,metro and train station are all less than 10min walk from the flat)
You are around 20min walk from major turistic attractions. In fact two are just outside your window - the Patheon and the Feira da Ladra.

The area is safe to walk around even as a single traveler. You have bars, cafes and a small supermarket near you or a bigger one a tram ride away. Alternatively, uber eats and glovo will deliver to you.
Cesar was very responsive to my queries. Very friendly host. He even helped me to source groceries for my arrival as I had to quarentine as I traveled from a red zone country.
Downside - the steep stairs, as other reviews mentioned so, not great for people with mobility issues, kids, prams or extremely heavy luggage. Cesar did help out with my lugagge at check in an checkout.
The bathroom is very small. Not a massive issue but if you are big you might splash water everywhere!
The internet is not very fast so some video calls might be a bit problematic, other internet work is absolutely fine. You will find this issue around most the old Lisbon. If you must have superfast Internet, you probably need to stay in another area.
Bonus point - if you are into swimming there is a public swimming pool near the apartment and you can pay as you go around 2 euro for a 45min visit! They also have yoga and some other classes. I was planning on swimming but all the walking up and down the 7 Hills of Lisbon was enough for me!
Across the road at the Copenhagen cafe you get a wonderful coffee and the best cadarmon bun outside Denmark!
I recommend César's apartment as a great base to explore Lisbon, Alfama and its fado and beyond!