The apartment was nice, practical and had everything we needed. It's location is in the heart of the picturesque Alfama district (everywhere you walk is a hill :D ) which has a multitude of beautiful viewpoints and lovely streets to explore. There's a coffee place downstairs that's very locals-oriented and feels very homey. Host was very responsive and kind. There's no self-check in so keep that in mind.
As a minor annoyance about the apartment: the bathroom fan is very loud, but I guess that could be somewhat easily fixed.
About the neighbourhood: There were some sketchy people around the neighborhood at night (mostly just guys wanting to sell drugs and loud homeless people), but if you're in a group you should be fine. It didn't feel dangerous. The neighbourhood is a mix of old and young. It's great. What may come as a surprise - it certainly did to our group - is that all over Lisbon people just outright piss on the streets and you may occasionally encounter the stench while walking through those amazingly beautiful streets.