Well, I'm the exact opposite from persiflage - I wouldn't count my opinion because I'm hopelessly biased on the other direction and RTD is my television god! Haha, aren't we useful? :D But for what it's worth, I really enjoyed it, and found it really interesting and informative, not just about RTD's writing process, but about the Who process in general.

(as for the books, I think they didn't print a lot of them to begin with - there was a huge problem when the book was published even in the UK, no one had enough copies :|)