There is a clear divide here based on the reviews I've read. The film has many supporters, almost as many detractors and not many in the middle.
Clearly, this is not a good watch for those who like plots served up on on a silver salver. Nor is it the typical teenage romcom where little is left to the imagination. However, I would urge viewers to look at it with an open mind and to try and understand the message that it is trying to convey.
I am by no means an expert in either psychology or psychiatry, but these are clinical fields in which the sufferer is often far removed from reality, but in their world they have THEIR reality. This is the point that has been sadly missed by those reviewers who accuse the film of having no plot, whereas it actually has two concurrent plots; one based on reality and the other portraying Sarah's decline into HER alternative reality. I totally agree that it does leave the ending somewhat ambiguous but so do many great films.......let the viewer use their own imagination.
I urge the detractors to watch it a second time with these points in mind. I did, and I enjoyed it even more that the first time around. Overall, I thought this film was well contrived and excellently executed.