Firstly, if you have already confirmed about travelling with PIA, have a nice trip.
I flew with them from Karachi-Islamabad-Frankfurt-Dulles Intl.-Toronto. It took us exactly 24 hours with some airport delays (not PIA's fault). The aircraft was B747 200 not combi or anything. I was with my family in economy class and I have to say that the service was excellent. Sure, you wouldn't find passengers all dressed up, wearing perfumes on their body, nicely styled and you wouldn't find the airhostess modern and talking as if they knew passengers through out their lives. Sure, most of the passengers and the crew will be ordinary looking. Sure the food won't be from McDonalds or KFC neither would you get first class treatment but I would say that they are GREAT.
As long as the age is concerned, our lives depends on nature. I mean, if you are muslim, Allah knows when you are going to die and I don't know about other people. PIA transports millions annually and Alhamdollilah there hasn't been any deaths in the last couple of years for PIA.
I would say that about 75% complaints about PIA people make are just silly. It is the habit of Pakistanis to believe what is told as true and spreading the word to other people.