Talk about tough sledding. At least with Cormac McCarthy's post- apocalyptic novel, you could stop reading once in a while and take a breather from all of the grim hopelessness. The film adaptation of The Road is a marathon of doom and despair. Viggo Mortensen is affecting as a father trying to protect his son from the elements and roving bands of cannibals. And sad-eyed Kodi Smit-McPhee is heartbreaking every time he asks his dad if they're ''still the good guys.'' But be warned: If you're looking for any shred of uplift, steer clear. All that said, if you feel like watching it a second time, there's a thoughtful commentary from director John Hillcoat on the EXTRAS, where he cites Mount St. Helens, Katrina, and 9/11 as influences on the film's visual style.
