This book is not poorly written - as in, the author is a decent writer.
It just doesn't tell an interesting story. It's not much about Alex MacIntyre, or if it is, it's pretty banal. It's full of pretty basic anecdotes of climbing in that era, and even then it's not that interesting unless you care about the politics of British mountaineering councils and organizations. I'm not sure the guy was that remarkable, or if he was, this book does a poor job of illuminating why. As for the 'birth of light and fast alpinism' thing, I don't know, it's touched on here and there I suppose, but it's hardly delved into. You more get the impression that the Poles birthed that idea, in parallel with their larger siege style ascents.
Anyhow, at some point the author says he hesitated on writing the book as he was not convinced of the story to be told. He was right, he didn't have the story. If Alex MacIntyre was impressive, I'm still not sure why.