Good site for recommendations on what shows or films to watch. I've rated every movie and show that I've watched for the past few years and this seems to be the most accurate on judging whether I'll like something or not before I've even seen it.
It potentially could be useful if you didn't know what you wanted to watch on TV- but users had better read the privacy policy first!
It requires geolocation to always be on. Also, if you log on through social media that means they get to rummage through not just your data- but of everyone you connect to.
Basically any time a site offers "Log in through Facebook/Twitter" refuse. An even better strategy is quiting the data harvesters entirely.