9/10 - Fantastic apartment in a fantastic area of the city, I highly recommend you stay here.
Pros:
The location is excellent; the metro and (one) train station is around the corner. Also for food, there is the time out market and loads of small bars and restaurants all on its door step. You can walk to all of the main old city attractions from here if you wish. The view over the square and out over the river is just amazing.
Space: The apartment is very spacious, lots of balconies, we never felt cramped at all!
Facilities: The tv, wifi, washing machine, dishwasher were all very useful and appreciated.
Cons:
Lisbon can be a tiring city, and the apartment is at the top of the building, the stairs might be an issue for some people after a day exploring (you definitely don't want to forget something when you leave!)
The nightlife around is excellent but draws some of the local drug dealers, they were all quite polite when offering their wares however!
Some random bits of the apartment need updating, obviously being used as an airbnb means things get broken/damaged, there were signs of DIY repairs and some minor things still needed fixing.