What a great film. Don't go if you are expecting "Alien", but it manages to combine great humour, suspense and lots of fun action with really serious themes such as inner city deprivation and predjudice. All in a non preachy way with believable characters (aliens not included).

A movie that combines the sad reality of everyday shabby neighborhoods of London with an amazing soundtrack and a somewhat "believable" sci-fi plot.
The acting was nice throughout and the setting was quite nice too. Unlike other movies, this one doesn't care in showing the "pretty" sides of London to viewers, but mainly focuses on building its story with a bunch of 15-year old gang members out to kill some bear/dog creatures with "glow in the dark" teeth, who like butterflies follow the scent of its killed female.
One thing that got me thinking after seeing this movie was the fact that it combines a sci-fi plot and some comic performances from now alien veteran Nick Frost with the true gritty reality of council estates located throughout the capital.
See it for the somewhat documentary side of it, portraying today's British youth, or for the simple chill of seeing a nice English movie.