My partner and I stayed in the Earth room for 2 nights and it was lovely. The place is just as described- a beautifully preserved, classic old Lisbon apartment with all the necessary modern upgrades. Clean, simple and cute design, nice appliances and furniture, very cool old neighborhood in a nicer part of town, and check in/communication was quick and easy. Although we didn't meet him (I don't believe he lives on the premise) Francisco was a very professional host.
Just a couple things to be aware of: as with most old buildings, there is some noise. There is really no way to avoid hearing the other guests and neighbors. Also, this is a shared space with 4 other rooms, potentially some long-term guests. This means that the shared kitchen and bathroom have a particular place for each room's belongings, and you may have to wait your turn. Was not a problem for us.