I saw this one almost a year ago on All Hallows' Eve. It's a bit old, but still gold! You really have to pay attention to 'know' what is happening and follow the story, this is not a cute anime to brainlessly watch. Perhaps you'd even got to watch it again some time. To better understand/follow the story and just so that it will make more sense.
The whole movie experience was pretty much like: every time you think you got it all figured out, you learn something new and turn out to be all wrong. Especially near the end of the movie. Just like Mima, the main character, I had a hard time figuring out if the stuff I saw was really real, of just... a trick of the mind. I absolutely loved all those twists and turns and the is-it-real-or-not feeling, not having everything spelled out before you.
I can highly recommend it to anyone who is not "afraid" of the anime genre. And, although it is a psychological thriller and a total mindfuck, I did not find it scary at all. Coming from someone who already grabs a pillow to hide behind whenever a suspenseful tune is played in a somewhat thriller movie.