Not one biblical writer claimed to speak authoritatively about heaven from firsthand knowledge.
You may also be interested in my article, “Heaven Is Real, but Heaven Is for Real Is Really Not: Ten Reasons Why I Consider the Movie a Dangerous Diversion” http://www.equip.org/articles/heaven-real-heaven-real-really/
Or my video, “10 Reasons Why Heaven Is for Real is Dangerous” http://www.equip.org/video/heaven-is-for-real/
For definitive discussion on Near-Death Experiences, see my book AfterLife: What You Need to Know about Heaven, the Hereafter, and Near-Death Experiences (Worthy, 2013), in which I answer such question as:
What is a near-death experience?
Do NDEs provide accurate information on the afterlife?
What are the liabilities of NDEs?
Can natural explanations account for NDEs?
What does the Bible say about NDEs?