Although it's a fantastic looking demon, and I admire the chutzpah of the director for showing it right at the start, I can't help think what an improvement to the story it would have made if the demon actually wasn't shown until the end.
Having shown the audience the demon, the film merely plays out like a whodunnit - with the murderer named at the start.
We immediately know, for instance, that the hero-sceptic Dr. Holden is plain wrong in his beliefs - demons DO exist (we've just seen it!).
Had the demon not been shown, we would have immediately sided and sympathised with Dr. Holden and believed, like he, that Karswell was a faker rather than a dangerous occultist. Had we believed this, the denounement would have been far more shocking and thrilling than in the original version.
What do you reckon?