We had a lovely stay at Daniel & Jerome's place in Barrio Alto, Lisbon. The apartment was clean, stylish, and well equipped with gorgeous views of the surrounding area. Our hosts were prompt and responsive, and provided helpful information for visitors acquainting themselves to the area.
The location has much to recommend it- the 28E trolley stops a block away (highly recommend the day pass for 6,40€), there's a grocery store and bakery within easy walks, and bars and other eateries galore nearby. We found it to be a great location for us to return to after venturing into the city, and think it would be a perfect homebase for a younger crowd looking to be in the heart of the city and its nightlife.
I believe the posting mentions these factors, but it's worth bearing in mind a few things that may be different than what an international visitor is used to: Lisbon is a VERY hilly city, and this neighborhood is no exception- the hill up from the main road is quite steep; the apartment is on the 3rd floor (European)/4th floor (American), with no elevator; and the immediate area is quite lively at night, particularly the fado bar across the street, which remains loud until the later hours. I think the apartment could be suitable many types of travelers, but is ideal for a younger group traveling light that doesn't mind (and indeed, is seeking out) the noisy nightlife that Barrio Alto is well known for.