I happened upon this film being played on IFC, and was pleasantly surprised. I concur with another reviewer's compliment on how the filmmaker allows the subjects to explain themselves and their beliefs without making judgment. In the end, the documentary does not seem to take a position either way, rather it simply documents Icelanders who believe in the "invisible world" and it's invisible beings.
The people interviewed in the film seem entirely of sound mind and body, and, in any case, seem to believe what they are saying.
What I found most compelling about the film is the way director Jean-Michel Roux and his crew crafted the film. The combination of images of Iceland, the ambient score, and the composition and style of cinematography give the film an almost narrative feel. The subjects seem entirely believable, which when combined with the style, makes this film so intriguing.