I second a lot of the other posts. It doesn't always hurt, though. Other than a newborn with a strong latch, mine never hurt. And even that was just at latch on.
The bad: (this might not be bad though) in that brand new stage - as in it happened when we were still in the hospital - you might fall asleep once baby is nursing. It might be a hormone thing, but as soon as he was nursing good, zzz.
No one else can get baby to sleep, and once baby is a little older, they won't be as willing to babysit a bf baby. But that also depends on your support system, are you an efficient pumper, etc.
Mom to a girl - 6, a boy - 4, and Baby - 2