Saw this yesterday and really enjoyed it. Urban nailed Dredd. I liked how they simply wrote a tight story that encapsulated a lot of what Dredd was about, instead of trying to be too "epic".
I loved the references to various names from the comics, both creators and characters, in particular the Chopper graffiti! No doubt I'll spot tons more second time round.
It's a pity the film hasn't done too well outside the UK. The planned sequels would be fantastic.
The one thing Dredd doesn't really show is how batshit crazy Mega City 1 is. Whilst it's an incredibly violent place, it's also full of the ridiculous and the absurd. With unemployment over 90% people do all sorts of things to pass the time. There are Fatties (the name doesn't do them justice, these guys are really huge) Simps (people who dress ridiculously) batgliders and skysurfers, and thanks to a man named Otto Sump, even making yourself ugly is fashionable. Heck the city had an orangutan as mayor once...
I spotted two fatties in the film and an Otto Sump store!