As a complete non-player of WoW, I am sad to say that this "documentary" didn't grab me at all, but maybe it has nothing to do with that? It missed the informative part I want from a documentary, and felt more like a journalistic work. Not wrong in itself, be the title of documentary made me expect something that I didn't find. Not for me, I guess.
Yeah I found it somewhat interesting the bit that I watched. I related well at the beginning about the early days of making games. Once they got into the whole corporate thing and big team and all there was a big disconnect so I lost interest. Part of my lack of interest I think is because one of the artists completed the spider animation and I want to get to work on my game! More interested in making progress! Been two days since I last was able to work on it! So... off I go.
I've actually never played a MMORPG, but I still found the documentary interesting, especially the parts about level and character design (designing and prototyping entire worlds then discarding them all). The part also about scaling the backend infrastructure was also interesting.