I spent one month in Bisera's apartment. It is exceptionally well located right at the Green Market square. It is a small apartment but very cute and practical. I really enjoyed spending time inside. It is located in the city centre, so everything is easily accessible. There is a nice gym nearby and great food options. You do hear a little bit of the street sounds in the morning, but it is not enough to disturb your sleep. I actually was able to sleep really well during the time I stayed here.
In terms of safety, the apartment's location is good. I had no bad experiences in the whole month I've been here. But in general, you need to have some common sense in the CBD area which means avoiding walking at night as much as you can and using Uber. This is more like a Cape Town thing though.
Overall, it was a pleasant experience staying in Bisera's apartment for a month and if you are looking for something in the city centre, I highly recommend the place.