i won't say too much because the other review by paul stock is sufficient enough to tell you enough of what you need to know.
i will touch on that many fans will be hesitant to see this or quickly judge this movie based on sylvester stallones portrayal as judge dredd. if this is you, please go see this movie and keep an open mind.
karl urban does a fantastic job of playing dredd, so much so, i forgot that it was karl urban under the helmet and believed he was judge dredd.
i promise you won't be disappointed. you might even walk out of the cinemas thinking that this is the definitve version of judge dredd, like me.