Absolutely no doubt about the location. Right in the center of the interesting attractions. Couldn't pick a better location.
Belem is a bit of a haul, but with the subway and bus system all is easy to get to.
Rossio is just a six minute walk (train to Sintra). All in all a great stay.
The apartment is older, so there aren't as many outlets as one might like, but minor detailsl Surprisingly quiet for being right on a busy street.
And the AC works great. We were there during a hot spell, and it was wonderful to come back to a cool apt.