Other comic-book-to-film efforts should learn from this.
It's simple: stay true to the source material. It's good - it's why it's popular enough to warrant a film in the first place.
The performances are excellent, Urban channels the original Dredd flawlessly, Headey is hardcore as the villain of the piece, and Thirlby plays a surprisingly convincing Anderson.
The settings are appropriately grim and foreboding, finally showing what Mega-city One would look like (something to avoid, clearly).
A sequel is a much-requested film by pretty much everyone who has seen this, and it's easy to understand why. For those of us who have been fans of Dredd for years, this is the adaptation we've been dreaming off (finally wiping away the stain of the Stallone nonsense).
Brutal, violent, visceral and relentlessly entertaining. If you're wondering whether to try it - do it. you won't be disappointed.