Hostal Neptuno felt like home by the time I left (I spent overall 11 nights there, in three different rooms). The staff is really, helpful and approachable: they went above and beyond to support me, providing information on how to best get around Havana, arranging super quick laundry services and booking collectivos for me. The hostal is in a colonial building with a recently refurbished outside that stands out from the surroundings buildings, and is perfectly located to visit Habana Vieja: the area is also really safe. The rooms are pretty modern for Cuban standards (bathrooms included): I found a good level of cleanliness and attention to detail that made me feel comfortable during my stay. Some of the rooms have a very nice balcony from which you can observe the life of the city, which I found very interesting, and the rooftop terrace is also a pleasant area to spend some time more peacefully and away from the city "liveliness". The only note, do not expect good wifi, as it is unfortunately the cases in many places in the country! Overall really recommended to enjoy Havana's capturing life!