There are some unrealistic elements to this movie, but only when you stop and think about it.  It's an action movie and there will always be some stretches of reality.  Harrison Ford delivers as does his supporting cast.  It will pull you into the story without any real trouble, you will find yourself routing for the President and telling the evil guys "take that".  In the end, you will feel good about it and you may even be inspired by it.  Enjoy!