I read it as well, a few years after it was published, heard about it via some show, similar to "In Search Of...", was prepared to be bowled over, wound up being unimpressed, and basically highly skeptical of claims of archaeoastronomy in general.
Well, let’s face it, in the sixties there was not much to read on Stonehenge.
They didn’t know anything.
We’re in a Renaissance on Stonehenge nowadays :)
As for reading and being skeptical, yes. Found it hard to believe.