Natacha's apartment is lovely. It's the perfect size for 2 people, great amenities (washer, full kitchen) and clean. There's a market down the street that's open late if you need any food or toiletries during your stay. The neighborhood is filled with locals - you will get the full Alfama experience by staying here.
A few notes for tourists who are new to Lisbon: the apartment is east of downtown Alfama, and the streets in Alfama are very difficult to navigate. We got into Lisbon at 9 PM and didn't have cell service or data when we stayed at the apartment, so we found it very difficult to find our way around. That said, if you speak Portuguese, if you're very familiar with Lisbon, or if you don't want to stay in a touristy area, then this is the perfect place for you.