Just as Facebook readies to announce its 500 millionth user, the American Customer Satisfaction Index releases its findings on the social network’s user satisfaction. Things aren’t looking very good according to the study, which was done in conjunction with ForeSee. On a scale of 0-100, Facebook scored a 64. That doesn’t sound as terrible as it is. Let’s look at that score comparatively.

A score of 64 puts Facebook:

**Just above the lowest-scoring airline from June’s survey

**18 points lower than Fox News’ website

Ouch. Sorry Facebook. Looks like the public doesn’t love you as much as you say, according to the ACSI. The project, started at the University of Michigan’s Ross School of Business, can’t deny Facebook’s popularity, but it can give consumers a voice. As Facebook braves the privacy backlash storm, it’s been able to lean on its own stats of rapid growth to indicate users’ lack of disdain for the social network, but the ACSI findings tell a different story.

As this is the first year the ACSI has included websites in its study, there’s little in the way of looking at Facebook’s user satisfaction over time–at least for direct comparison. And there are a multitude of other factors to consider, including the type of website, consumer and service provided.

But given the current war Facebook is battling, it will be even more difficult for the social network to defend its place as more and more consumers catch on. Perhaps its the media’s constant nitpicking at Facebook’s privacy options, or the regular pendulum of “hot or not” as a semi-permanent fixture of pop culture. Whatever the case, Facebook still has some work to do if it plans on keeping its consumers happy for the long haul.