If I was to point out a problem with open data, it's that it has the potential to break our social institutions by facilitating aggressive min/maxing behavior on a large scale. It's not that Goldman Sachs is going to use the data against the general public -- they're going to do that whether the data is public or private -- but you make it public and then the middle class can use it against the poor (and then the poor are going to revolt).
For example, suppose we create a good, easily accessible map of places to live and put down all the information someone in the housing market would like to know: Home prices, tax rates, quality of the schools, etc. Now home buyers can min/max those variables when making a purchasing decision. In general that's good -- when we buy a home, having that information benefits us. We can find a place that has extremely low taxes when we don't have kids in school, and choose between the places with excellent schools to find the one with the lowest taxes when we do.
But then local governments react by trying to find a niche. They let their schools go straight to hell in order to attract childless professionals through low tax rates. Or they zone all the low cost housing out of the school district so that they can maintain good schools at a low mill rate because everyone who can afford to live there is affluent. What they most certainly don't do is provide good schools or other government services to poor people, because that has a deleterious effect on the value for money that middle class people are looking for when they're shopping for a tax jurisdiction, and when they do that they lose their tax base and thereby their ability to continue doing it.
Of course, such things happened before public data, but you make the data more widely available and you make the behavior more common.
And before the libertarians get too happy about this state of affairs, recall that the de facto default defense against aggressive competition is collusion. Which we [pretend to] ban in the private sector, but between governments they just call it centralization and "federal standards" and impose it on you from the top down the second they can break a filibuster. Which is, of course, miserable and inefficient because it destroys local control and creates a systemic failure if they get it wrong.
Which isn't to say that the data availability is net negative. The incentive it provides is for governments and corporations to be efficient, and efficiency is usually (indeed almost always) beneficial. But the data lets the user of the data decide what to optimize for. So the problem comes when the thing we choose to optimize for as individuals is not the thing we would choose to optimize for as a society.