My wife and I spent 4 nights in Ana & Antonio's apartment and loved it! It's very close to a metro stop that we used every day. The apartment is very clean and had plenty of room for us. We were able to make coffee in the room every morning, and even do laundry. We loved leaving the balcony doors open and looking out over the streets. The hosts were very responsive and helpful with everything we needed! If we returned to Lisbon, I would definitely stay here again.
If you cannot manage very steep steps then this apartment will not be for you, but my wife and I had no issues with it.