To weigh in, socially and economically the Dark Ages went crap. They aren't called 'Dark' because thhey were bad so much as because we are metaphorically in the dark about what happened, what with literacy going down and limited sources.

For the most part feudalism replaced the highly efficient Roman bureaucracy, coinage and banking kind of fell apart and kingdoms couldn't even retain standing armies, Latin was bastardized into a bunch of other languages...

Farming and metalworking advanced though :lol