We highly recommend this to any couple hoping to visit Lisbon. The location is excellent, the views from near the apartment are spectacular, and it's only a short stroll downhill to the centre of Lisbon. One tip would be that if you take a metro to Martin Moniz from the airport, it's best to take a tram or bus up to the castle rather than walk, as the footpaths aren't all very suitable for transporting large luggage items.