Actually, 7 hours is just about the perfect lenght IMO for this type of game. Unless it\'s an RPG, I tend to lose interest in a game after 8-10 hours, and a FPS adventure game with 7 hours of stuff is perfect.
Some of my favorite games of this type are much, much shorter:
Bionic Commando
Metroid I and II
Super Mario 3
Goldeneye
ZOE (a bit too short)
GTA3
You should also double their estimate:
FFX "can" be finished in 30 hours. It takes most people 60-90 with secrets/char leveling
Goldeneye "can" be finished in a couple of hours, again, it takes people 8-10 with most secrets... and much much longer with all.
GTA3 "can" be finished in a few hours, but most people played it through for 10-20 hours.