Great place and great hosts! The apartment is in fact location on top of a restaurant so it may be a bit loud until 11pm but after that it’s quiet. The restaurant is great, by the way ;)
It is located in the center of Alfama and the charm of the old neighborhood.
The hosts are very communicative and very accommodating, with very fast responses and good tips about Lisbon.
One note: the bathroom is very tight, so it may be a burden for taller/larger persons to access the toilet.