Some researchers say that near-death experiences give us as much information about the afterlife as walking around an airport in Beijing gives us about life in China. Given the limitations, and the fact that near-death is not the same as final death, what can we learn about the nature of life in the afterlife from the collective experience of the many hundreds of thousands of accounts of NDEs?

Actually, quite a lot: 1) That consciousness can exist outside the body. 2) That there is an afterlife/other dimensions. 3) That we can be reunited with our loved ones. 4) That we may experience in full graphic details a life review where we get to experience the consequences of everything we have thought, said, and done. 5) That everyone goes to the afterlife, not just those of a particular religion. 6) That animals go to the afterlife. 7) That our lives do have a purpose. 8) That the more love we show, the closer we will be to God.
Read What Near-Death and Other STEs Teach Us about God and the Afterlife.