The flat is really well located, in a very typical building in the heart of Lisbon. The castle, downtown, main squares, the Tagus River can all be reached by foot. There are many restaurants nearby (Hugo also provides a list of restaurants to try, which in fact are local treasures, not the touristic options), and the nightlife can also be easily reached fast from the flat (Bairro Alto or Cais do Sodré).
Hugo was a great host, made us feel really welcome and was available in case we needed something. We had also Time out magazines in the flat, cards for the public transport and some self made guides to the cities (As mentioned with the restaurants).

The only downsides are that the flat is in the 4th floor w/o elevator and there are some constructions on the south side of the building which is a bit noisy in the morning. Nonetheless, it was overall a really good experience and we would recommend it.