Even didn't meet the host in person, Joao is a good host who replied fast and provided many info and tips. The place is great: The flat and the view are as fabulous as shown in the photos, especially the terrace. The interior is well-maintained and well-decorated. Joao also provided travel information in different languages in the flat. The location is good too, with a little bit of hiking from Martim Moniz (easy access to tourists' must-go Tram 28 and 12), and bus stop of No. 760 (directly to Parca do Commercio). A chained supermarket Pingo Doce is right next door opens 7 days a week. The only disadvantage is that Joao doesn't provide WiFi but a 3G dongle for laptop. As more people don't travel with a laptop but only mobile devices now, it had been a bit inconvenience when traveling spontaneously as I did (e.g. needed to look up things at last minute).

In short, great experience at Joao's attic flat, and had some nice days in Lisbon! Thanks a lot. B)