The acting was terrible (Justin Long was ok), the horror wasn't there, the dialogue was terrible, it was cheesy, the ending was insanely predictable, and the special effects were substandard.
Anyone who has seen it can tell you about the scene with blood shooting out of the main characters nose and mouth. It was such a bad scene. She is shooting blood from her nose and mouth, and I mean shooting it, think Adams Family or the Black Knight from Monty Python. When her boss gets covered in her blood he very calmly asks "is it in my mouth?" Not "ARE YOU OK!" Considering she was loosing enough blood to die. Not even "AHHHHH!!!! CALL 911!!!" Just "is it in my mouth? I think it's in my mouth."