He takes minor things such as the title sequence, and makes them interesting, emphasising their importance and not disregarding them to the story - A good example of this is the title sequence in Snatch. He makes the titles slide in, bounce in, fade in, does whatever possible to capture your attention. He employs freeze frames to make you really see the scene, rather than passively being given it. He puts an emphasis on slow motion to really bring detail to the film, and it really shows his strength as a director as seen so well in Sherlock Holmes.
He clearly has a passion for gangster type stories, as most of his films have pretty brutal fight scenes, and although sometimes a little disgusting to watch, he maintains a comic undertone to his film. It may be from the light hearted music constantly playing in the background of his films, or it might be the quirky actors he uses such as Gerard Butler, Vinne Jones and Clive Owen. He has a grubby mise-en-scene which evokes a gritty atmosphere, and then has these comedians fighting. What a contrast.
And as for these actors, the chemistry he creates within the script between the characters is so great to watch, and endearing to the audience. Whether best friends or deadly enemies, it's a thrilling watch, you never really know what turn the film is going to take, and it truly does keep you on the edge. Plus, they usually have this 'bromance' type relationship involved which everyone loves to see.
So, he knows how to write a film, he knows how to direct a film, and he knows how to edit a film. Why hasn't he made more?! It's probably because he loves his British cinema, which is a given, so Hollywood has never really taken a chance on this incredibly talented filmmaker. But now Sherlock's proved to be quite the success, he's sure to be a hit with the producers in the Hills.