The game is pretty short. Certain bosses require a certain strategy to beat otherwise it could be frustrating. Its a linear path game, but if you are into Star Wars this story is a must. The gameplay itself is nice because of the many types of ways to kill people using the force powers and stuff.
Basically this game will have dozens of copies in the used section within a week or two after release due to people finishing the game and not doing anything with it. Now there are two endings but they don't require a whole replay. The hardest difficulty setting has to be unlocked so for all the achievements you'd have to play through it twice. There are also Jedi Holocrons that you can collect that give you different lightsaber colors like red, blue, purple, gold, green and black or they are saber crystals that can give your saber added benefits. That gives it the minimum replay value.