I would also agree this movie is extremely creepy & well-made, even if it has only passing resemblance to the book on which it was based. I will however, take a bit of an issue with the comment you made about taking the events that happen to John Klein as either real or grief-induced hallucinations. Perhaps it was both, but no amount of grief will allow one to drive 800 miles(pretty sure that's the number given in the film) in a few hours. Also, when he takes the recording of Indrid Cold's voice to a sound analyst, the man says the voice wasn't created by human vocal cords. I suppose one could say someone was mucking with John's head & made a computer-generated voice, but there's no evidence in the film for that. In any case, Klein's 2ish hr 800 mile drive was a clear indication something truly odd was going on.