We had a wonderful stay at Ricardo & Carla's. Ricardo was very kind and stayed in touch during our stay to make sure we had everything we needed. The apartment is cosy but ideal for two people who know each other very well - the bathroom is on the small side, with a tainted glass door... so it could get awkward.
It is ideally located, in our favourite quarter of Lisbon with all restaurants and bars on your doorstep. Bring your earplugs if you don't plan to party all night as it is a bit noisy until late. We did sleep very well with ours.