First of all Martim Moniz is the nicest place you can stay, it has very easy accessibility to metro and bus, since you are 2 stops from Caixe sodre where you can take a train to belem (you should taste the falvour "Pasteis de Belem" there) or a ship to seixal (the other side of the Tejo river).
The apartment offered by Joylisbon is very new, and it is apropriate for a couple that wants to enjoy their weekend or vacation, you have really nice look to the castle of "São Jorge" from this apartment, in the interior part the photos posted are real and it looks the same as they appear.