This could have been a much better movie, but is delivered mixed results instead.
Much has been done to inform us that active duty SEALS were cast, because actors just can't portray the roles realistically nor with enough authenticity. That's a load of puffery; an actor's job is to portray, and make you believe that they are telling the truth. Train the actors: teach them how to move, how to hold their weapons, and how to react. They don't actually need to be SEAL qualified, just enough to perform the correct actions, because that's what movies are all about: making what's on the screen look believable.
What Act of Valor has instead are real-life SEALS pretending to be actors. You can tell who the non-actors are because all their lines are delivered as if every sentence is a declarative statement: flat and without emotion.
As long as the SEALS don't talk, the scenes are brilliant. Military fans won't be disappointed with many sequences showing what SEALs do best: raids, room clearing, firefights, insertion by SDV, and HALO jumps. Act of Valor also marks the first time that I've seen SWCCs and MEATS (Maritime External Air Transport System; underslung boat delivery by CH-47) represented in any movie. In fact, the scene where the SWCCs come in with mini-guns blazing is one of the highlights of the movie.
The movie plays like a 101-minute long first-person-shooter video game. The SEAL team is largely reactive: being dispatched globally from one skirmish to another, where accomplishing one mission just means earning the opportunity to move on to the next mission level. When you really come down to it, the plot doesn't much matter for this movie, serving largely as a vehicle to showcase military hardware and delivery of tactical missions.
Go watch this movie for the action, for SEALS serving their quiet and brutal profession. Everything else in the movie, from the storyline to the acting, unfortunately don't quite do justice for these elite warriors.