We had a lovely stay in Belem during our trip. The apartment looks lovely in the pictures, but is even nicer once you arrive. The enormous private balcony really made staying here worth while.
Check-in was quick and easy and we received great information from the host about the surrounding area and getting into the centre of Lisbon. We also had a hire car and never had an issue parking around the property.
I would definitely recommend this as an option just outside of Lisbon with very easy transport options into the city centre.