What does the U.S. get out of the deal?
A nuclear arms race in the Middle East and in all likelihood, a nuclear war in the not-too-distant future. Iran is very close to getting an ICBM, and with a little help from Pakistan and North Korea, they can fabricate a warhead small enough to fit on top of the rocket.
At that point—or even before—we detect tunneling at a suspected Iranian test site, followed by the installation about the time Iran announces a successful test of a of monitoring equipment and other required hardware. Then, the USGS detects a seismic event consistent with a nuclear test. A few hours later, a WC-135 Constant Phoenix aircraft detects aerial radiation and dust from the blast—nuclear weapon. By that time, the Saudis have their own nukes, as do the Emirates, Kuwait and Qatar, plus delivery platforms.
Not long after that, Iran decides to go after Israel, or the Israelis pre-emptively attack Iran. It ends in a nuclear exchange and millions die. Thousands of U.S. military personnel are caught in the middle, and Iran will likely target them as well.
That’s when the 3 am call reaches the White House, and the next President is left with the disaster unleashed by Barry. Of course, Obama won’t be worried—he’ll be “retired” to his beach-front mansion in Hawaii, just waiting to jump in front of the camera and blame his successor for screwing everything up.
Short answer to your question: What does the U.S. get out of the deal? A world of trouble (at best); a nuclear holocaust at worst, with millions dead.
Currently, the only organization preventing this nightmare is the Israeli Air Force—and there’s no guarantee they can sufficiently blunt Iran’s nuclear ambitions.