Good:
The stay was generally really nice as the location is super central!
The apartment was clean enough and the sheets were clean, too!
The little balcony provides a nice view.
Quick response time and very friendly when there were questions!
There is a friendly cafe right downstairs that opens early for coffee and food.
Less good:
As the location is super central it can be quite loud (metro, cars etc). I sleep with ear plugs and we still woke up by the neighbours on the 5th floor (this apartment is on the 4th floor, so be prepared for stairs).
We had to book the accommodation fairly last minute as the previous booking was cancelled though we had to accept the high price.
We were unfortunate as the electricity in the main hallway shut off during night so we stood outside in the cold for a while. Luckily we were able to call the landlord who organised someone to open the door for us.
When we stayed at the apartment was a homeless lady who stayed at the entrance each night (4nights). She did not want to take money we offered and she would go further away when we approached the door to enter.
My summary:
Great location and it was clean. If the price is ok for you and you can walk stairs then I recommend the stay.
My advice:
Take an Uber from the airport as that is very cheap in Lisbon. Make sure to give the driver a tip :)