First, I'm a major Michael B. Jordan fan. As usual, his work was excellent as John Kelly. I noticed some reviews saying the plot had been done before, even comparing it to The Bourne movies, but keep in mind that Without Remorse was written years before those movies. If anything, Clancy used the plot first. It's still fairly predictable, but not because it has been done to death before this book was written. As for the age difference between Jordan and his character, this movie tells his story BEFORE he becomes John Clark.
Gender in terms of SEALs is open to creative license for the sake of entertainment, particularly since she played the role well. It's nice to see something different sometimes, and the fact that Jordan is Black should serve as a reminder that skin color doesn't take anything away from the character. The only reasons I didn't give the movie 5- stars are that there were some slow parts and unrealistic talking during action scenes, i.e., when the sniper is firing at the team and Jordan is explaining the nature of the set- up. Overall, entertaining and worth watching for action lovers.