Port Harcourt defies description, really. It's that shite.
Well, the bits I saw on my one and only (and definitely last) visit were, anyway.
Was early noughties when I was young and dumb and unknowing. As NB says, not a good part of the world to be pale-skinned. There were guys working for Total and permanently based there who took being lifted for ransom as a pastime, it happened that often. Only made the news back home if they weren't released on payment or it dragged on for a few days. Total would pay up after a brief negotiation to get the price down to a relative bargain-basement level and they'd usually be released same day or the next. Usually local gang-bangers with all the gear and no idea. Only really a bad day out if MEND or another "serious" outfit lifted them.
Port Harcourt was okay-ish (by local standards) until about 2004/5 when MEND and the copycat groups got serious about violence and kidnapping. @Northern_Biff mentions his company upping sticks at the time, and many others did as well. The net result was a vicious circle of money and jobs leaving the city thus leading to more crime.
Warri (another oil city) had been through a far more violent period not long before, and aside from one oil major had very little in the way of big business. Curiously, this led to the formerly violent youths being so desperate for work that they were hard grafters ('04, '05, '06).