As for game completion time, I believe it is an acceptable amount of time for an FPS. (amazon.com)
Fixed an issue where Ikrie's Challenge would count towards the percentage of game completion of the base game. (wccftech.com)
Once the main story campaign was complete, there was little else to do other than go out and find the game's staggering amount of collectibles, some of which did nothing else other than pad the player's total game completion score. (shacknews.com)