I fly out of Newark regularly because it's less of a hassle from my home in upstate NY. Been using this airport for ten years and in all honesty, can say that I've never problems (forgiving weather, cancelled/delayed flights). There is on-site airport self park and valet parking, as well as off-site parking (via shuttle bus). If you're driving to the airport, you'll want to pay attention to the signs as to which terminal your flight departs/arrives from. This will allow you to park closer to the terminal, otherwise it can be a hike and hassle especially if you're schlepping bags, small children or cranky spouse or relative.
The airport is large and you "commute" between terminals via a tram which runs regularly every 5-6 minutes. The stops are clearly marked and there are announcements on-board, however, you'll want to pay attention.
I especially like Terminal C (Continental) because there are lots more shops, restaurants and services (love the Departure Spa if you're waiting for a flight. Terminals A & B also have services.
Taxi service is outside of each terminal and you'll want to make sure you grab one with a meter--not a gypsy cab or limousine looking to pick up a fare. Certainly ask what your estimated fare is to your destination and if tolls are included to avoid getting ripped off.
The airport is run by the Port Authority of NY/NJ. Much money has been pumped into the airport to bring up its facilities and its a welcome change.