In this blog, I earlier mentioned one writer's take on Dr. Alexander's book.
Here's another, this by John Horgan, that appeared in a Scientific American blog. His post, What Should We Do With Our Visions of Heaven—and Hell? raises some technical criticisms of Dr. Alexander's report on his experience (of near-death). But Horgan then adds some more experience to the discussion with a report of his own "travel" (or NDE or OBE or whatever) during an experiment in his college years.
I get the sense he still doesn't know what to make of what he encountered. It's worth reading, I think, so I won't try to summarize, or even introduce my take on it.
What I do find puzzling are the reader comments to Horgan's article: many, maybe most, are hostile to the idea of even considering these possibilities. That mindset reminds me of the mindset of the medieval church (even until not-so-long ago) pronouncing ANATHEMA! (Meaning, thanks Wikipedia, "either set apart, banished or denounced".
At least nowadays we don't burn at the stake "heretical thinkers" -- those who explore questions that the Establishment had decreed settled.
One put-down of Harvard Med trained neurosurgeon Dr. Alexander was to the effect, What kind of real scientist can he be given that he wears bow-ties? (Sorry, in a hurry and can't put my finger on the exact quote, but it's in the response to Horgan's article.) In other words, Dr. A doesn't dress like us, so therefore he's not to be credited. Anathema! Ban bow-ties! Block off your ears to those who experience what is not to be believed!