In my experience, MA drivers are slow and drive very defensively/deliberately, at least on the highway. Like they are all 80 years old in a large Buick. This can lead to them sometimes seeming to be erratic on the roads compared to those who drive in a more "fluid and rapid manner." They don't react as you'd expect and take a while to maneuver, like when changing lanes or merging.
NH has its share of bad drivers. A classic around here is a lifted truck passing 2-4 cars at once on a two lane road right before a blind curve. I haven't been here long and have already seen some near misses with head on collisions.