Great potential........but disappointing!

I expected so much more of the film. It started well and was pretty scary for the first 45 minutes or so but then dwindled into nothing very much. It seemed to lose track of where it was going and what it wanted to say - if anything. The acting in parts was pretty dreadful (particularly the daughter of the guy from the high rise - what accent was that supposed to be?). The film had great potential and could/should have raised some really interesting political/social/environmental issues - a great debate starter, and some of the extras supported this but it never happened. There was no explanation of what had happened and the 'happy ending' was more than a little contrived and left me feeling distinctly unsatisfied.