Intrigue, mystery and monstrosity.10/10
It is interesting to see what people think of this movie, since it is, in fact, quite unique (though it bears some of the trademarks of Clive Barker's writing). Even though it might seem a bit cynical to say so, the movie is just intricate enough to deflect those that need standard Hollywood plot hooks, and layered, so that if you expect to be fed, you will see a normal monster flick with lots of monsters and a disjointed plot.
Those who need a linear, specific and untangled plot line will hate this movie, because the story lies, like in the novella, partially between the lines, or in this case, partially off screen, in comments and the imagination.
Another possible hang-up is the ending, of which I can say, without spoiling it, that it is not entirely good and not entirely bad. It is, in fact, not very defined at all, which I know sends some people into raging tantrums about that they didn't get to know what happened, but to me, and to many others, I'm sure, just adds another dimension to the story - the dimension of speculation, and, in addition, the point that great disruption has a tendency to cause ripples that extend quite far.
There is definitely moral here, but of a rather different kind than the standard Hollywood in-your-face-at-the-end-of-the-movie sort of display. Summing that moral up is simple, even though it is not quite that simply displayed; prejudice and the human tendency to hate the different.
I love this movie, even though, as many of the reviewers have noted, the expressions of the actors (with the exception of David Cronenberg, who does a wonderful appearance) are rather tacky. I'm not sure they are entirely to blame for their rickety appearance and lack of depth, though, seeing that these are common problems in converting literature to screenplay.
All in all, this is a great movie, provided that you do not expect it to be a standard horror movie.