Our congregation was/is the opposite from what others are saying about the book study. It was always had less attendance than than the other meetings, swinging at around 80%. The Service Meeting and Congregation Bible Study is swinging around the same now, where our Sunday meeting is ranging anywhere from 90 to 100%.
Me personally, I hated the old book study arrangement. Hated getting off of work, and getting dressed up to go sit in some hot apartment or cramped room in a house. Or in the winter, gettting off work and wanting to stay home and cozy, but having to get dressed up again to sit somewhere for an hour discussing the most boring material. Psychologically it messed with me too because I knew we'd have another meeting either the following night, or two nights later depending on our situation with sharing the hall with another congregation or two. I'm glad they combined the book study with the school. Now if only they'd get rid of the midweek meeting entirely, especially since the service meeting is useless considering we're largely wasting our time out when out in field service.