Full Disclosure: this was my third time in Lisbon, so I fairly know my way around the city.
I found the apartment exactly as advertized: very clean, welcoming, and comfortable. Hosts were very professional and responsive to my queries. Coming in, you get an introductory binder with everything you need to understand and get around town: city map, public transportation map and prices, suggestions of places in and out of Lisbon to check out, etc. For a small extra, they also offer a private driver service from and to the airport, which I highly recommend. Their drivers made me feel like a CEO, with their professionalism and courtesy.
The apartment is very conveniently located in Mouraria, just north of the charming Alfama neighborhood and a 10-minute walk from the breathtaking Castelo Sao Jorge. You will also easily access the area's gorgeous vintage points ("miradouros") from this apartment. There are small grocery stores a stone throw away from the apartment, and the nearby Praca Martim Moniz has a large supermarket, a drugstore, and an AVIS car rental office. Also nearby: stops for the 28 and 12 tram trains, which I highly recommend if you want to take an old-fashioned slow scenic tour of the city. Point of caution: Mouraria, like Alfama, is a very hill-y neighborhood, so keep that in mind if you have back or knee problems.
Overall, I had a great time using this apartment and I will get in touch with these hosts for my next stay in Lisbon.