It's also not adversarial; the government has substantial advantages at FISC that Google doesn't have. Which supports the notion that FISC wasn't conceived of as a regular Article III court, but rather as a different kind of check; more of a review board than a court.
Obama said yesterday,
"On this telephone program, you've got a federal court with independent federal judges overseeing the entire program," the president continued. "And you've got Congress overseeing the program, not just the intelligence committee and not just the judiciary committee, but all of Congress had available to it before the last reauthorization exactly how this program works."
This is slippery and brings to light a problem with FISC. Its judges are independent, but the process is not. The FISA process (necessarily!) begins with the premise that NSA has a Constitutionally unchecked authority to conduct foreign surveillance.
I think this would be fine, were it not for the fact that NSA seems to be transitioning from a role that was principally involved in nation-state intelligence to a role that is inextricably bound up with law enforcement. You can see the problem when Mueller starts talking about what it would take for FBI people to dig deeper into NSA work product. The FBI shouldn't have access to NSA product to begin with.