No pun intended - we are talking about two individuals who need to be the center of attention. And while that may sound like a match made in ... well not heaven, but also not hell. Their attitude though ... especially hers ... the title suggests that she hates herself - but it is the perception of herself that she hates.
On the other hand, if someone goes to the lengths she goes through ... if you have seen the trailer you know what I mean. If not, don't worry I won't say what I mean. Suffice to say it is something amazingly crazy. And if you thought she was unlikeable before ... well let me tell you, you will not like her more after that inciting incident. That of course as anyone can guess spirals out of control.
The introduction the director gave (video message) before the movie began was funny. Suggesting that only smart people will understand and like the movie. That said, of course he is not insulting anyone not liking the movie. There are quite a few reasons why some may at least mildly annoyed at the movie. Or at least the characters and their poor decision making.
Make up is really good, the diving into the head of the main character and seeing a version of what she thinks her future holds for her appears as sudden as it goes away. And you can't always tell when it begins - you can mostly tell that it is a dream sequence though.
Suspend your disbelief and go on a ride with a person that thinks she deserves attention ... remember: this is just a movie and do not try this at home.