Carla's apartment is very conveniently located, nicely exposed (it gets natural sunlight in the morning, for many hours), has all appliances one may need, and is a great base to explore Lisbon. However, it is quite tiny and you can hear when people upstairs move around or talk. For us, this was not an issue at all, but if you are a light-sleeper or plan to spend longer hours in the apartment itself, it may be.
The communication with Carla was easy and check-in and check-out went smoothly.