The door chain is good if the door is strong and reinforced, otherwise they can kick it in, and the door edge would break in splinters.
The peep hole is good except you only see who is Directly in front of the " peep hole" .. you can't see the man, leaning against the door, that is holding your next door neighbor at gunpoint. Many instances where they robb several apts in the same floor
I had several cases of people lost in the building asking for directions, never opened , one lady claimed she was legally blind, and needed help to read directions.
The worst case was a fist fight in the hallway a man with a knife attacking a couple , the woman starts banging on my door to let her in to escape from the attack...I figured that if I open the door, the fight would continue inside my apartment , so I called the cops ...