Greetings,
Port Moresby can be a little unpredictable. However in 3 years we have not had any major incidents. I did have my car broken into twice and my wife lost a purse with phone, kindle reader and all her cards. It was a bit of a hassle to get credit cards and stuff stopped, but we didn't end up losing any money. However in this case it was my fault for not being careful. Someone saw me put the bag in the trunk. If I had not done that they wold not have bothered breaking into the car.
There are car jackings and theft and rape of course, there are simply place you go and don't go. We don't have any fear when traveling around the main roads and shopping areas, but we are always careful. Last week there were a couple of car jacking attempts that expats got out of okay. Typically thieves want your stuff. I f you ever are confronted just give them to he stuff and they will go on.
That said, there are plenty of safe areas to enjoy in the city. If you do got to events like cultural shows or street markets I always take a couple of local boys with me. Make friends with locals and they will help you out a lot. Bottom line, know where to go and where not to go, stay alert and get to know the locals.
PM me if you want to know anything else.
Steve