As far as location goes, you cannot do better than this place in all of Lisbon, not just Alfama. Antonio is a very good host with excellent communications and very committed - he couldn't meet me as I arrived very late (the self check in works smoothly by the way), but made it a point to come see me a day or so later with handy tips, and a bottle of wine!
The apartment, set in an old building, is very modern, with great views of life unfolding from morning till evening. It has all the amenities in the kitchen. But the bathroom is very small and only an intimate couple can share such a space. It does get quite cold in the winter.
The location is well served with Trams 28 and 12, but it's just great to walk from and to this place.