Marcia's place is lovely - it is the nicest place I have ever stayed in Portugal. It has a lovely tiled balcony with a great view, a great kitchen/living room, fast wifi, a good shower and is really well located in a quiet area but only minutes from Belem Tower. The communication with Marcia was also great, and she personally checked me in and showed me around.
My only slight gripes were the single beds which were both very hard mattresses (a big soft double would be nicer), and the fact that the noises from her daughter's apartment upstairs were bad (she came home after 1am and was moving things around on the wooden flooring which kept me awake). But if you're a heavy sleeper and don't mind a hard mattress, this place is pretty much perfect!