Two Scoops is solid, but it's also a $14 ebook, whereas Effective Django is free. Not really apples to apples.
It seems to me the only durable advantage to the free version is that if it isn't working out you can abandon it after 15 minutes at a fraction of the cost. If there were a credible way to sell knowledge products "satisfaction guaranteed" I'd think that people would be a lot less sensitive to the difference between free and $14.