The book came out in 1987 but I didn’t read it until the early nineties. Whitley Strieber experienced much ridicule for writing it, especially the part about how the aliens would effectively rape people via the use of anal probes.

I believe his experiences are genuine, even if they didn’t physically happen in the real world, as the supposed aliens are said to be able to alter a person’s perceptions and present a false reality in their mind. Even Strieber himself said the beings had more in common with folklore tales of fairy kidnappings or demonic encounters.

In answer to your question though, the thing about it that strikes me most is how even 34 years later Strieber still has no definitive answer as to precisely where these grey aliens originate from, or the exact nature of their alien agenda.