I would definitely recommend staying at Simone's place!
We had a great time in Lisbon! The apartment is really nice and very new and clean. There's everything you might need and the location is superb, right in the heart of the old part of town with several restaurants and little supermarkets very close by.
The highlight of our stay was our host Simone! I've never had a better and more caring host. She went out of her way to make us feel like at home in her apartment. She even picked us up at the carpark (at Santa Apolonia - good idea to park your car there!) when we arrived late in the evening. Communication with Simone was great and easy, she replied very quickly and sent us a long list of great things to do and see in Lisbon! Thank you, Simone!