I haven't driven through it much since it was completed - I moved out of Boston in 2005. As a now-just-visitor I find driving through the central artery tunnels even more stressful than on the old elevated 93, but that could just be a lack of familiarity thing -- I don't drive when I visit Boston, only if I'm flying in to Logan to head to the cape or something. It is, however, _really_ nice not having the freeway cutting through and the greenway is gorgeous.