The spirit world is a place of waiting, working, learning, and, for the righteous, resting from care and sorrow.
It's not the end of our journey--just a stopping point until the resurrection and our being assigned to the degree of glory that we qualify for. But as the manual said, we don't just sit around. There is work to do! A lot of it. There are two parts to the spirit world--paradise and prison. Those who chose evil works over good are in prison. There they will recollect all that they did wrong in life, and suffer with the memory. The spirits in paradise are the spirits who were righteous. While they may rest from the worry and care of the world, they still will be at work sharing the Gospel to those in spirit prison. Those who did not have a chance to hear the Gospel in their mortal life. Then those souls are able to choose if they want to accept the Gospel or not. They won't be forced.
On earth, worthy members who are able to enter God's temples are able to do work for the dead. The dead are temporarily separated from their bodies. They cannot be baptized or receive the other saving ordinances for themselves. So those on earth do it vicariously. On this side of the veil, we don't know which spirits have chosen to accept the Gospel or not. As such, members try to do the work for all that they find so all have the chance to accept or not.
So the spirit world for some is a time of working. A time of teaching. A time of reflecting. A time of choosing. A last chance for some. A time of meaning and purpose for others.