For the average joe, I wouldn't imagine huge differences at all. The enviroment is squalid, cramped, expensive. In Rome, tenements house families packed into rooms. The lower floors are noisy and vulnerable to crime. The attic freezes you in winter and boils you in summer. There's no financial support for the poor either - none of modern social provisions, although they did have a corn dole if you had a permanent address. But then, the supply of cirn was variable according to circumstance. Augustus was obliged during one shortage to exile "useless mouths" from Rome. Claudius got pelted with stale crusts from an angry crowd.
Water supply is an interesting issue. It seems local initiatives sometimes did supply cleaner water via aquaducts direct to homes in places like Herculaneum. In Rome, with much denser population and high rise apartments (the highest was nine floors - most averaged five to seven) the supply of water meant a walk to the local fountain and back again, upstairs, with a heavy load of water. I'm not hugely convinced the supply was entirely clean, certainly not by standards, but most likely better than typical towns that relied on wells or nearby rivers. Water from natural watercourses was used by human and animal alike for all sorts of things and if you were downstream of a settlement, the water was unlikely to be as healthy. With poor urban drainage and stagnant water malaria was rife in Rome as the imperial period progressed.
In short, despite changes in culture and facilities, conditions between imperial Rome and Reformation London resulted in pretty much the same life expectantcy.The Tiber did not achieve the same terrible reputation as a sewer in the way that the Thames did but there must have been similarities.