The apartment is super close to the Santa Apolonia station and has plenty of bars and restaurants close by. The view of the port is amazing and there's always ships to see and there's a supermarket in the station for necessities.
The stairs in the building are a little uneven so be careful going up to the apartment, otherwise we had a brilliant trip. Daniel was always on hand to offer advice and give tips and was really easy to contact.
You can stroll into town, it should take 20 minutes if you're not stopping at the bars and restaurants, or jump on a bus, tram or metro. I'd recommend getting a daily ticket for €6.30 for sightseeing which you can use all over the city.