Really loved my stay in Francisco's place while I was working remotely from Lisbon. Belem is a great neighbourhood to be in if you're looking for a quiet, peaceful and relaxed area. Its about 20 minutes away from central Lisbon so keep that in mind for sightseeing (the distance wasn't an issue for me).
The apartment was safe, clean, cosy and had everything I needed - it really felt like a home away from home. Also Francisco was very communicative and gave many local recommendations.
I highly recommend this place for a cosy stay in Lisbon.