Just re-watched... damn good.

Just re-watched this in glorious 3D Blu Ray. This movie was damn near perfect. The action and directing are great. It makes great use of 3D.
The actors nail their respective roles, particularly Karl Urban and Lena Headey.

The story was simple, but entertaining.

I'd love to see another Dredd movie with Urban. The challenge would be what to do with the character. We never see or learn much about Dredd other than he's very effective at what he does... killing perps with extreme prejudice but without the wise-cracks that you would typically expect in this sort of flick.

Would a sequel be better served if we learned more about the man behind the mask, or should it just re-tread the same territory as the first one?

Dredd -- the movie -- owes much to Robocop. I remember that the sequel to Robocop wasn't nearly as good as the first one. There's only so much you can do with a character who is an android. But seeing the man behind the mask would take away a lot of his mystique.