Don't come if you're taller than 5'9" or 175cm. The apartment is in an old building and the roof is very low. If you're a tall person you won't be able to stand up in most parts of the apartment. The hallway up the stairs is also very small and narrow. You need to climb up the stairs to the 4th floor and there is no elevator.
Other than this, this apartment is ideal. I was here for 3 weeks and was comfortable. The internet is ok, you're in the middle of Alfama and near many restaurants and bars. The apartment is also very well equipped.
The host was amazing, he personally came over one day to deliver fresh sheets and towels.