It's interesting because it's Grant Morrison's attempt at a definitive Judge Dredd. (Also, it looks like gold compared with the runs by Garth Ennis and Mark Millar that preceded it.) This was part of the Morrison/Millar "Summer Offensive", in which they took over 2000 AD for two months. Apparently, Morrison thought for ages about how to write Dredd... and then eventually made him a one-dimensional bastard.
I quite like it, but its plot's as one-dimensional as its anti-hero. Dredd sums it up when asked if he has a plan. "I got my plan right here!" he roars, club in hand. That's the general tone. Criminal ex-Judges from Titan prison colony take over Mega-City One, forcing the Judges into exile out in the Cursed Earth. Their leader is Grice and he's a psycho. (This is a sequel to Mark Millar's Purgatory, which concluded immediately before this began.)
You now know everything that matters. The plot is just various repetitions of tough people going to confront Grice without a plan and encountering a shit-kicking. This happens... uh, three or four times? One of those is even one of the baddies. The story's dumb as a post. It is, though, hard as nails. It's full of utter bastards who'll commit any kind of murderous act. They'll break your jaw and smash your ribs with a sledgehammer. They'll repeatedly smash McGruder's face into the floor, then strap her to a bike and send her plunging off the city wall.
As bad as any of them is Dredd. He does the following:
(a) He shoots a man (normal for Dredd) with an incendiary bullet (yow). Burns him alive. That's his first kill in the story.
(b) The convicts take a prisoner who'll die if Dredd doesn't surrender. He's not interested. "Osterwold's one of the best, Judge Bhaji. She knows the rules." Result: she's chained to four motorbikes that drive off in opposite directions.
(c) On abandoning the Grand Hall of Justice, our heroes realise that they don't want to leave everyone in the iso-cells for Grice to free. Dredd's solution: "This qualifies as an emergency situation. We flood the cubes." (One drowning victim's last words are that it was only a parking offence, for Grud's sake.)
(d) It's the end and the right anti-heroes have won. The convicts are heading back to Titan. Unfortunately, security's just been torn to shreds up there, so won't they all just escape again? "I thought of that," says Dredd and presses a button. BOOM. Ship explodes. Problem solved. Frankly, though, this is feeble compared with this story's other bastard actions, so as a final punchline it's underwhelming.
The other interesting thing here is Morrison's use of Dredd lore. He builds set pieces around the Judges' exotic bullet types (incendiary, armour piercing, etc.), the remote-controlled Lawmaster bikes and even Walter the Wobot.
I quite like this story, but it's in a half-and-half zone. As a Judge Dredd epic (i.e. ignoring its off-world prequel), it's too short and simple to stand comparison with stories like The Apocalypse War, Necropolis, etc. It's resolved too easily for a story that kicks the Judges out of Mega-City One itself. There's lots of juicy ultra-violence and Dredd nearly gets killed, but ultimately it lacks the weight of even Judge Dredd vs. Aliens. That said, though, Purgatory and Inferno together lasted twenty weeks, which is more substantial. As for its extreme content... well, it's violent, yes, but this is 2000 AD. John Wagner's done all this before, and better. Look at what Morrison achieves with Walter the Wobot, for instance. (Answer: very little.) I love Walter and I was delighted to see him, but Wagner would have made his appearance funnier and/or more meaningful.
The "Purgatory-Inferno" double-header is still fun, though. You could do worse.