To some extent I knew what to expect... On the other hand this film was completely shocking. I wouldn't say it was an enjoyable experience but it was certainly evoking and incredible.
From the start of the film there was a lot of hand held which was very noticeable and disconcerting. Which worked for the film. It gave the very normal beginning an undercurrent of discomfort.
Throughout the entire film was uncomfortable and on edge. I put this down to the sound work because it was just fantastic. I would imagine a lot of foley was used and there were moments when the sound gelled so well with the film that it was almost unnoticeable yet if you listened, it was completely unnatural to that moment or setting.
Another thing that really stood out for me was the special effects. They were ridiculously good. Throughout the film Portman's skin rippled with effects so subtle that you barely noticed until it became much more obvious and important towards the end. The sound effect that went along with this effect was so perfect it made my skin crawl too!
Overall this was a fantastic film. It's subtleties really balanced the gore and shock factors. I would say the creep element is very Pan's Labyrinth yet the gritty handheld realism grounds it in reality even throughout the fantastical scenes.
Watch it! But be prepared!