content: Which ones, specifically? So far I haven't seen one you couldn't opt out of. (IIrc anything that transmits personal data is opt-in on the release channel.) Their targeted advertising system is also the only one I've encountered that (at least on paper) does no tracking whatsoever until you click on an ad. It's true they started bugging people more about sync and downgraded the security of that system in the face of user error though :-\