I liked the sound effects. In the opening scene where Alex is singing that goofy song and it immediately cuts to the title screen with eerie sound. Then later when Alex opens the tent to see the bear and that low rumble that sounds like a growl starts pulsating at intervals. It really builds tension. Plus the attack scene left me traumatized for weeks.
A lot of people have said how the movie has a feminist subtext. Possibly but I think more people are more comfortable hearing a man get torn to pieces than a woman.