I agree, the drip feed of information into the radio show was very effective at building the tension and creepiness. The script and acting are excellent, I really want to listen to Grant Mazzy on my radio! I liked the doctor character as well - the crazy scientist type who pops up from nowhere and explains what's going on, 50's B movie style, very funny. There's a lot of clever humour throughout the film, for example the Canadian French vs English language thing that becomes a key plot device.
When I saw the film I didn't know it was a based on a book. To me the central idea reminded me of Neal Stephenson's Snow Crash. I found out afterwards that there's a copy of Snow Crash lying around in the movie somewhere, although I didn't notice it. Its about a year since I watched it and its just started nagging at the back of my mind that I really want to see it again.
That post credit scene! - well I'm finding it difficult to discuss without venturing into spoiler territory, but if language helps to shape reality then maybe they found a way to shape their own reality just how they want it. And it was very cool!