I truly respect both Gaiman and Riddell, and I enjoy a lot of both of their works. There are some absolute gems of quotes and art in this little book that I would love to create posters of to have in my classroom.
However I also think its entirely healthy to say I have different viewpoints to other parts of Gaiman's outlook, in fact, he says so himself in the first section of this book!

Some gems I loved:
> "Everything changes when we read."
> "Fiction builds empathy. Fiction is something you build up from twenty-six letters and a handful of punctuation marks, and you, and you alone, using your imagination, create a world... and when you return to your own world, you're going to be slightly changed."
> "The urge, starting out, is to copy. And that's not a bad thing. Most of us only find our own voice after we've sounded like a lot of other people. But the one thing you have that nobody else has is you. Your voice, your mind, your story, your vision."

Something I differ on:
"People who know what they are doing know the rules, and know what is possible and impossible. You do not. And you should not...if you don't know it's impossible it's easier to do."

Oooh I'm sorry there Neil but if anything, knowing the rules and being told something is impossible, powers me more than anything else. Knowing the rules helps me play the system built against me, and knowing that what not to do, or what people have said is impossible is wrong, fuels me to be the one to do it.
Without learning those rules as a foundation, I would never feel confident enough to break them. How do I break something I don't know exists? Pure luck? Learning what I'm supposed to do first gives me a power to knowingly not. Knowing what's wrong gives me evidence and reason to tear it down.
There's a privilege and a confidence in choosing not to know and push onwards anyway that I envy, but also could never justify.