Interesting stuff. I think that many people might be surprised about what their "online signature" actually looks like when aggregated and posted by a third party. I deleted my various social media accounts a number of years ago, partially because I realized that it is NOT a game, and privacy is a good thing that is easily lost and difficult (or impossible) to get back once compromised. Aside from that, Facebook started trying to monetize the site in earnest and it became rapidly apparent that I, the user, was the product. Obviously I still engage in some amount of online "socializing" since I am posting here and elsewhere, but it generally does not include PII (personally identifiable information).
Anyway, I may be a bit overkill with my privacy angle, and there's nothing wrong with using stuff like Facebook to keep in touch with distant relatives and such. Just be careful how much PII and behavior indicators you put out there because you might not realize how it will look to someone that does not "actually" know you IRL. Digital Shadow might be an interesting wake-up call for some people, and despite being a marketing gag, I can see it having potentially positive effects.