This detail is a major one. This would mean the NSA cannot simply log on to Facebook and query for whatever they want. It means the system is simply a way for companies to comply with FISA requests, something that they were already required to do.
So: even though Twitter doesn't use PRISM, there is really no difference between what the NSA can access on Twitter and what they can access on Facebook. Twitter just complies through some other manner.
Google has claimed these requests are infrequent and narrowly focused, and they have requested permission from the government to publish some statistics. I hope they get it.
The threat to this model is the idea that a FISA warrant might not be required until monitoring has gone on for 72 hours, but that was just as much of a threat with the prior model, where the data were manually extracted and sent by the company instead of using the automated dropbox setup.
There's nothing necessarily wrong with something like PRISM (especially since we don't even know what it is), but the choice about whether it's right or wrong belongs to the people as a whole, most certainly not to a few people happened to have grabbed that power.
What's the point of democracy and accountability if it's unclear what people are accountable for nor what you're voting on? This kind of system should never ever have been introduced in secrecy.
Does the public go down and tell the Admirals how to staff a warship? Or what controls to use when deciding to launch weapons? Those are life and death decisions where the military essentially handles its own oversight with Congress and government civil servants involved at the higher levels to handle public interest in accountability and oversight. Yet I don't see the public up in arms about that.
Now, if the people say they don't like Prism and don't want it then the NSA should gut it; that's the right of the people to decide.
But I wish we wouldn't be so quick to jump to the idea that the public must personally audit and review all such government programs as a rule, because as far as I can tell from the seats I've sat in the public has never actually believed that in general at all, and are normally quite content to allow their Congressmen and our shared values as citizens (for those actually doing the work) to provide that oversight.