I absolutely loved it! The apartment is even better than the pictures and the view is amazing! It is located near the famous tram 28 and close to the metro (both 6 min walking). Also, with a 20 minutes walk you can reach the Rossio train station (with trains for Cascais), the Sao Jorge castle or Praca do Comercio.
Helena and her husband are great hosts, she even made us a personalized scheduled for visiting places in Lisbon. Check in and check out went smoothly.
I definitely recommend it!