knowledgeable yes, annoying and full of himself, also yes
I'd imagine the reason the author gets on peoples tits, is that he speaks like every other agency pond life we have all probably had the misfotune to have to speak to, pander to, and basically hope for a scrap from his table.
Granted this one seems to know what he's talking about, which frankly, puts him in an exclusive group of 1 with his fellow agent scum in my experience.
It's a bit like reading a Dawkins book when he's on a roll:
+ you agree with him, he makes excellent points
- he comes over as a bit of an arsehole, completely full of himself - the odd possible 'convert' is more likely to be wound up by his attitude and stop reading, than listen to him anymore (this is from the experience of gifting his books to friends and family only to be informed they couldn't stand his attitude after a few chapters*)
It's a persona not best suited to persauding the greatest number of people to your point of view imho.
*The Magic Of Reality it like this... he makes a statement at the start about 'this is not about god, no talk about god and athiesm here'... then littered through the book are aside snide comments about the stupid god believers, etc.. does he not realise that this puts certain people off ? he just can't help himself. An otherwise excellent book, remains unread of my mothers bookshelf, as she does want to be preached at like a 5 year old.