I stayed there 2 weeks and it's definitely one of the best airbnb I've stayed at: the location is ideal if you want to run in Lisbon: go down the beautiful Avenida Da Liberdade and you can run along the Tagus in no time, or go through the Parque Eduardo VII / green corridor and you're in the fantastic Monsanto park before the end of your warmup :)
The room is great, plenty of space to work / relax. The rest of the apartment was good as well. Internet / wifi was a reliable 50Mb with low ping.
Finally, the hosts were absolutely amazing: kind and available. Definitely a great address in Lisbon, I'd stay there again if I'm back in Lisboa ;)