Cusak's great, not the most versatile roles, but check out High Fidelity. (Aside - he was the main character in Grosse Pointe Blank, where I grew up. Not being from NY, LA or Chicago, it was cool to see places I knew in a movie).
Anyway, I watched Identity 3 times & still didn't get it, even after my wife explained it to me. My idiocy aside, it's still a good movie. I just don't like deus ex machina endings.