After trying to play this movie a few times over the past little while and encountering nothing but sound problems (the audio would just quit after a few minutes), it's perhaps ironic - if I'm using the word appropriately - that the movie would be so acoustically involved. It's certainly not something I would have expected, as the main draw to the film would be the promise of aliens, attacking and something about a block. I read a slight blurb comparing Attack the Block to another great film, District 9. I don't think the comparison is fair, so I'll leave it there.
Perhaps you would like a brief plot synopsis. Basically, some aliens start crashing down to Earth around this block and it's up to a small group of unruly teenagers to put an end to them. Or at the very least, run around scared out of their wits by these monster/alien creatures, providing many opportunities for surprise, gore and - to top it all off - humour. The gang is led by Moses, and they start off fairly despicable, by mugging a poor helpless woman. This immediately forms a stereotype in my mind about England in general, and that would be to be very careful of kids. They are all out to mug you: they have a system that should be patented, and seems to be present in any movie coming out of the country. As the movie progresses though, it becomes clear that they're the heroes, and it doesn't become difficult to cheer them on.