What has changed in Cuba after the announcement?
Cuban citizens are still not permitted to speak or read freely or do anything freely without the fear of imprisonment or even death. Cuba is no closer to becoming a democracy and you have to wonder if this move will embolden other tyrants to take Americans hostage in order to win concessions.
U.S. policy towards Cuba was codified into law under the Cuban Liberty and Democratic Solidarity Act of 1996, and the Trade Sanctions Reform Act of 2000. The policy changes announced by the President are an overreach of his executive powers under the law. The official legislative history of the law clarifies that the President has power to tighten economic sanctions, but not to ease them beyond the baseline set on March 1, 1996.
BTW, Gross was an aid worker. He was traded for 3 convicted spies. It looks like Obama didn't learn anything from the Bergdahl trade.