We had a lovely stay in Maria's flat! It is just perfectly decorated and was so comfortable to be in. The plumbing is a bit old and some of the drains tend to be a bit slow but I think this is to be expected in such an old building and didn't really affect our stay at all.
The flat is located in a very lively area of Lisbon with lots of nightlife so it can get a bit loud, but this wasn't a problem for us either. One of the most stunning views of Lisbon was just about a two minute walk away.
Maria was a lovely host - we never were able to meet her but communication with her was easy throughout our stay.
I'd really recommend Maria's flat and would happily stay there again (hopefully soon)!