So having reviewed the series Blue Exorcist time to look at the movie.

The story begins with a storybook as a flashback sees Fujimoto read a story about a demon who got everyone to stop working and have fun leading to the demise of the village until an exorcist drove the demon away, from then every 11 years a festival celebrates this event and guess what, that's happening in this movie.
Before the festivities can begin, Rin Shiemi and Yukio are after a sinister Demon Train but a series of events cause part of the city to collapse releasing a rabbit demon child from a shrine.
As the barrier is being restored demon attacks start becoming more common while Rin is forced to look after the demon child having taken blame for screwing up the mission but while Rin and the rabbit demon bond it becomes more apparant that the rabbit demon is causing these problems.
The story was careful not to play the same card that it's been playing the whole series which is of course, demon bad, must kill, while it technically still does, it tries not to make it too much about that and focus more on the humanity and bonding between Rin and the Demon Rabbit Child, however while I like the direction and risk that it took to not play the obvious Shonen mistake and just make a giant battle, it did take up it's entire budget showing off how much it can fit on screen and not look like a giant graphic mess, don't get me wrong, it's impressive but it's just distracting.
Dub feels more polished this time and I don't appreciate the baiting in making me read the manga by introducing characters not due to appear yet. Yes I am aware that there is a season 2 airing at writing time, I write that in the sense that it hadn't been announced yet and it was still 2012.
Final Verdict: A nice change of pace from the boring overused Shonen movie plotline but spoiled a bit by it's ambition to try and make a graphical masterpiece.