Bad- leakage problems, sore nipples, over/under production issues, time/leaving baby (pumping, engorgement from forgetting to pump, baby not taking a bottle), the first month, being a paci, nighttime waking a that never seem to end,
Good- breast feeding relationship, no formula to buy or prepare, lots listed in pp.
Good and bad vary for each bfing relationship. I listed all I could think of for bad but none of them occurred with all my kids. I've had 3 exclusively bf (bottles of bm count) and 3 supplemented with formula for convenience. One was bad enough at the beginning I almost quit but they all had months of a good bfing relationship.