This is NOT a horror film. I don't know why people keep saying it. Sure, there are some horror elements, like gore and the supernatural, but the film isn't really trying to scare you.
With that out of the way, you'll find an interesting, if at times meandering story, with a satisfying payoff at the end. The plot revolves around Nevena, a mute girl who has literally lived under a rock her entire life until she gets turned into a shapeshifting witch by another ancient witch.
The conflict between the two is central to the story, with Nevena remaining hopeful to find a place among normal humans, while her mentor is cynical and sees any living thing as simply as "blood, not playthings."
An interesting film, the protagonist's growth is quite heartwarming, though the slow-paced dream-like narrative (which is used to convey the passage of time from the perspective of an immortal being) may not be for everybody.