I chose Residencial do Sul for cost reasons - I wasn't looking for luxury or extra facilities, just a cheap, central place to lay my head at night, and RDS delivered!
Right next to Intendente metro - which meant it was easily reached from Aeroporto with just one change from Red to Green lines in 30 minutes - it proved to be just what I wanted. A no frills, inexpensive, unfussy bedroom.
Patricia gave me a helpful orientation when I arrived and didn't mind storing my bag until I could check in a few hours later.
When I did check in, I was pleased with my room - top floor, at the back, effective air conditioning unit, very quiet (apart from the thud of the lift arriving). Basic facilities, shower unit, wardrobe, TV, all clean and in working order.
No wifi, no bar, no breakfast room, but that was fine - Lisbon papers to be very well served by 3G anyway.
Overall, it's a 6-7 out of 10, for a two star hotel. Very happy to recommend to travellers on a budget who don't mind a basic level of comfort, to save money for Ginginha...