Earlier quoted context omitted.
This is much less of a privacy issue for me than is when Google reads my email, for example. Here, I'm aware of the fact that my data (location, appointments, flight plans) is read, because I couldn't get the recommendations/information otherwise. So, it's much more of a consensual act. If they use this data for other purposes (ads/paid recommendations/geotracking), that is a separate issue, and I would be very mad.
Google doesn't "read" your emails. The information completely secured from human eyes. A computer looks for words and phrases and tries to match ads to email content. Sometimes this is helpful, but the advertisers only receive anonymous data and no humans at Google or anywhere else read your data. Source: http://support.google.com/mail/bin/answer.py?hl=en&answe...
For now. But what happens when data mining technology increases to the point where they can deduce real facts about you as a person from all this data they're collecting. I think this is what people mean when they say Google "reads" your email.