I enjoyed this movie a lot, and I agree with a lot of the other boards that this will be a cult classic. But I especially enjoyed the many homages to 1979's The Warriors directed by Walter Hill, some are obvious like a small gang of kids, 7 or 8. But others more subtle, such as them running for their life onto te subway platform only to release that they stopped chasing Them a long time ago.
I'm not so sure. The Warriors revolve around a gang has to find their way home through hostile gangs' turfs in one night.
Attack the Block revolves around a young gang who treats their housing estate as their turf. Any stranger ends up on their turf gets robbed. The gang is a bit like the bandits on a road, waiting to rob travelling carriages, during the medieval era.
However, when the aliens turn up, the gang rallies around their turf to fend off the aliens. No different from those in a castle fighting off invaders during the medieval era.
It's better to compare Attack the Block with films like Assault on Precinct 13, Slither, Straw Dogs and such.