This little apartment is very convenient to the metro. Wandering around the streets can be a bit confusing because they all seem to look the same. We never felt unsafe in the neighborhood at all. At first sight it seemed a bit sketchy until you realize that all of Naples is covered in graffiti/ street art.
The only thing I would mention is that the shower area is small and the shower curtain tends to blow in on you. Just tuck the curtain back and or clip it to the little clothes line hanging there.
We loved the apartment and would definitely stay again.