I'll admit, I figured it out about 30 minutes in (when they wheeled the convict into the room). I even saw the "twist" at the end coming a mile away. So after I figured it out, I didn't really care who got offed next.
And I had some questions. Was the "Larry" they found in the freezer a personality? What about the Corrections officer that got shivved in the back? Was he a personality?