I'm not surprised by some of the negative reviews. This film starts off with a clever premise, that mixes in a Spanish social justice psychopath, reminiscent of "Dexter", with a literary bent and the world of high stakes corruption.
What follows tracks well, up to a point, where the lines between fact and fiction blur. What you are left with is open ended and up to you to interpret, with no solid conclusion.
Its a "tree falls in the woods" deal that is somewhat disconcerting. I can fully see why people who like a linear plot, with a tidy outcome might find it annoying.
I certainly felt a little disorientated but ultimately I was left feeling more positive about this film, than not. Sure its plot is light on detail but it makes its points with an enigmatic cleverness. The cast is well chosen, the characters interesting and the acting excellent.
It also makes some very pertinent points about the distance power places between people from distinct social strata, notions of corruption and the inequity of establishment justice.
7/10 from me.