Snapchat for advertising: it's good, but it's not great

It’s been a punchy couple of weeks for Snapchat.
It announced that there are 10 million daily users in the UK.
And this was followed by the Wall Street Journal claiming: “Snapchat’s Teen Fans Wince as App Catches On With Their Folks”, with one in six American users over 35 years old.
Really? Is Snapchat really growing so fast that it’s gaining on Facebook?
And following the Facebook pattern of growing fast among the young, and then into the middle-aged mainstream, i