The basic principle is simple: the characters, all young Londoners from a variety of backgrounds, speak to the audience, Talking Heads-style, about issues that affect them: music, alcohol, drugs, sex, and even some politics. Some of the comments are funny, some absolutely hilarious, and a few are even quite profound.
As in real life, there is a broad cross-section of society represented, and if sometimes the characters seem a little stereotyped, then this is not necessarily a bad thing; it helps the audience identify with - or laugh at - some of their more outrageous suggestions. There is a supermarket shelf stacker, a fetish model, a teacher, and a young lady who is "far too busy to work". The audience finds itself alternately roaring with laughter at some of the unbelievable points of view put forward, or nodding in sympathy. Some of the characters are racist, some are sexist, some are fascist. Strong Language means exactly that: it has not done its job if it does not shock as much as it amuses.
As the film progresses, we discover that there is order to this apparently random collection of anecdotes. A single central story starts to emerge from the most mysterious of the characters, around which the others continue to discuss their various issues. And in the last three minutes of the film we discover something else about all of the characters, which I won't spoil for you here.
Writer/producer/director Simon Rumley clearly has a gift for words on a par with, say, Quentin Tarantino; and in a sense, there is a distinct similarity in directorial style as well. But Tarantino is equally happy letting hard action tell the story, while Rumley, possibly because of budget constraints, has had to rely on words alone. Fortunately, it works brilliantly, although it is a lot more effective watching it in a cinema or with a group of friends than on your own.
Overall, I rate this film highly, and would not hesitate to recommend it. Here is proof, as if it were needed, that it is not always the worst films that fail to find a decent distribution deal.