The apartment is very well located. It is a 20 min walk to Alfama, but since there is nothing much to see on the way, I would take the metro or bus. There are two metro stops (Anjos and Intendente) which are very close and easily reached.
At night there is a pizzeria at the corner of the entrance to the alley, where there are always several people, so the place is rather safe to walk through at night.
The studio space is as decribed - I would make sure to ask for a large pillow as the one provided was only cushion sized. Also, the air inside the room is rather damp and humid (opening the window helps a lot) but it can get stuffy.
Claudia and Jose respond to messages very quickly also.