Gorgeous apartment in an excellent location! The view is fantastic, and gets even better at night when Lisbon lights up!
The amenities are perfect: dishwasher, clothes washer (with dryer included), microwave and regular oven; you name it (even a capsule coffee machine)! The TV has multiple channels and the Wifi is free and fast.
Public transport is available close at hand: the Rato subway entrance is a few blocks away and there's a bus stop close by that'll take you right to the Sete Rios railway station (where you can depart for Sintra, for instance).
The hosts are quick to respond and have many suggestions and advice for local attractions and restaurants. Check-in and check-out was as easy as pie and we were left wanting nothing!
The only minor gripe that has been mentioned before is that the elevator indeed can be quite loud at times. If you're a light sleeper, I suggest bringing ear plugs because it's sometimes used into the night (especially on the weekends; weekdays seem to be very quiet) and can wake you up. Of the six nights we stayed it only ever bothered me -- my girlfriend didn't even notice -- on the first night (a Friday), so we don't consider it a major issue in the grand scheme of things.