Probably because it's more of a screenplay/novel than conventional journalism (strictly style wise, it's a great story!). Entertaining, but very drawn out for the amount of useful information provided.
I like how it makes no affronts to being 'objective' and is quite clear that the author doesn't expect to be believed outright due to the content and story, but will go ahead and fill in the holes in time. That's some great serial structuring. It's written very well, which, let's be honest, a lot of journalists are not equipped to do. By nature, reporting wants prose to service it, not the other way around (save for HST and "Gonzo" influence). It is a very captivating subject indeed!