I definetly recommend it. The apartment is great and it is right in the middle of Lisbon. Diogo is a great host and recommends a lot of very nice places to see in Lisbon. I will for sure return to Lisbon and will definetly stay again at Diogo's place.
There are lots people singing in Placa de Camoes but from the living room you will only hear it very little (and anyway - such great music is really nice to listen to) and nothing at all from the bedroom.
There are small super markets around and lots of nice places to have dinner or coffee. Tram 28 has a station right next to the apartment and you are 9 minutes walking distance from Elevador de Santa Justa.
Cais de Sodre station (from which you can catch the train to Cascais or the bus to Belem is 5 minutes walking and Rossio station for the train to Sintra is around 12 minutes walking.
So, great location, great apartment, great host in a really beautiful city that waits for you to discover it:)