Overall I enjoyed my time at Ricardo's place.
The good: The apartment is huge for a studio. I've stayed in 2 bedroom apartments that were much smaller. Location is really good too, specially if you're arriving in Lisbon by train. The location is within walking distance from Entrecampos train station. It's also close to subway station and supermarkets. The internet was great, I could work from home without any issues. The apartment has good insulation and sound proofing. Despite being exactly in the flight path, I found the place really quiet and the airplane noises never bothered me.
The bad: compared to other AirBnb's this was the least prepared to receive guests that I stayed in Portugal. The cooking utensils/pots were pretty bad, no dishwasher liquid, no laundry soap, nothing other than the basics. Also, the washing machine wasn't working, which I unfortunately only found out in my last night (but that wasn't so bad since there's a laundry shop on the building next to it)