Luis's place is central enough to be close to the action but enough away to not be too busy. It's just on the last part of the hill going down to the city, which means a bit of exercise walking back uphill but that's probably a good thing. ;-) There's a good range of restaurants and shops within walking distance and the metro station is quite close.
The place is a good size for two people and well equipped for cooking, etc. Bed and sofa are comfortable. The only drawback is caused by a leak coming into the apartment from upstairs. Luis is well aware of it, and apologised, and has plans to get it fixed. However, some water comes in and the kitchen ceiling has a stain and smell. With luck, Luis will have it repaired and cleaned up soon.
The apartment has restaurants and a bit of foot traffic directly outside downstairs (no cars, it's a big stairway) which might be a bit noisy for some but it didn't bother us very much.
We found it a great base for exploring amazing Lisbon.