One of the biggest reasons that people are scared to come visit us is the fear of driving in NYC. After all the places that I have gone, and growing up in the Los Angeles area, I have come to recognize some of the cultures of driving. For NYC it leans towards aggressive. Mind you not as bad as Italy. The most aggressive is still Naples. But really that is the only fault. Other places I have driven have more dangerous traits: Laissez-faire attitude to the laws- Places like China where the lines on the roads are worn off from everyone driving on them. Unawareness- Utah, I can only guess they are so involved with what is going on in the car they have no idea what is happening outside of it. Speeding- route between Los Angeles and Las Vegas, if there is empty road in front of you its going to waste.
The aggressiveness here really slows down traffic. I would say that even with more cars on the road traffic in Los Angeles seems to move better because there seems to be more of an acceptance of traffic. It becomes mind-numbing but and along with that comes the idea that everyone is sharing the goal of getting to the destination. Here it is totally normal to cut off traffic and back it up 30 seconds to shave 3 seconds off your commute. People will get to the absolute furthest point before merging lanes or exiting/entering the freeway. That is the one that really bothers me and I have been honked at for not allowing cars to merge. (It makes you think- they are mad because I'm not letting them cut me off, I still don't understand it either.)
The worst drivers I have seen though are cars with New Jersey and Pennsylvania license plates. I guess it is because they have to commute even more. We saw a car (Pennsylvania) with a spike sticking out directly in front of their front tire. So if you didn't let them merge in front of you, you'll end up with a scratch down your car or a popped tire.
Like most places though, as long as heavy traffic times are avoided it is much less stress. There is also no real reason to drive into Manhattan, public transportation is good and finding parking is expensive and a pain.