I've stayed in numerous airbnb's in different locations in Lisbon, giving me a good comparison. I did give this cutie 5 stars, but there are a few things to note.
Location: This apartment is perfectly centrally located, and to the Avenida Metro stop takes 5 minutes downhill, and ten minutes uphill (it's a trek, and I had a backpack and strong legs/lungs). I found a shortcut of stairs (love all the secret ways one can go around in Lisbon) going up. On the other side of the neighborhood, it's a ten minute walk to the big Pingo Doce for groceries...easy and convenient, but again it's up/down--welcome to Lisbon :)
The apartment: Put together very nicely, and the big perk is the deck...If you have sunshine, you won't want to leave. However, construction was going on across the way, so my view and sound was affected by the noise and image of "construction stuff". By the way, construction is ALL over the city, so many neighborhoods are affected, not just this one. I would ask next time about neighborhood goings-on.
Yet, the owners included everything you need inside, and it's a nice, modern place.
Value: This is a tough one, as prices in the city are going up and up, and I was here during low rainy season. I have spent ten euros less/night in Lisbon for similar quality/location, also in the off season, so I think considering the couple of disadvantages (hills for those with luggage, and the construction) the price could be adjusted a bit.