That catch is this -- your privacy may be at stake if you register your drone. Forbes' John Goglia did some digging after noticing some contradictions between the FAA's FAQ section and what they stated in a legal filing. He emailed the FAA and the DOT's public affairs office asking simply if registrants' information, like their names and addresses, would be made available publicly. The FAA's response: 

Until the drone registry system is modified, the FAA will not release names and address. When the drone registry system is modified to permit public searches of registration numbers, names and addresses will be revealed through those searches.

And DOT's:

Initially the Registration system will not have a public search function. The FAA plans to incorporate a search by registration number in the future. Names and addresses are protected by the Privacy Act. The FAA will handle disclosure of such information in accordance with the December 15, 2015 Federal Register notice.

This is certainly a substantial cause for alarm, especially considering the fact that children as young as 13 can register their drones. We don't know yet how private information will be searchable, or how on earth names and addresses can be revealed through searches (FAA) but still be protected by the Privacy Act (DOT). The fact is, if you do your due diligence and sign up on the Federal Drone Registry, according to the FAA and DOT, your information (name and address) will be available to the public through a search of your registration number. Whether you call that an invasion of privacy, a safety precaution, or whatever else is up to you.

Source: Forbes