Too didactic to work.
Not dissimilar to an overreaching Hollywood B-movie, Tesis scotches the popular assumption outside of Europe that all foreign films are intellectual and arty.
It's not that bad really, it passes a couple of hours and it's a great deal better than 8mm, it's just too riddled with plot holes and far-fetched behaviour to become absorbed in.
It's as if Amenabar has focussed too hard on trying to say something about screen violence and the voyeuristic human response to it and missed the opportunity to make a plausible film as a vehicle for his ideas. It's not clear what he is trying to say, perhaps even to him.