Ok I saw it on Thursday and loved it. It was a very good movie.
So lets discuss why such a good movie has tanked at the box office. This time of year is usually a slow time but this movie has made next to nothing.
I read last week how 3D is not doing so well so that's where my guess will go as to why this movie has tanked. Since this movie did not have a 2D option correct? (In this area all the times seem to be for 3d and no 2d option was available) I know they charge more for 3d and so maybe that along with releasing the movie this time of year has done this film no favors.
Edit: Ahh I see an above poster did see it in 2d. I wonder why they didn't even offer that around here.
There's defintiely a 2D option, I saw it in 2D. But, really when it comes to 3D movies, 2D screenings are rather hit and miss. A lot of the time theatres don't bother with 2D and when they do, they make it very inconvenient to catch a 2D showing. In fact it's only been in the past few months that theatres in my area have been making an effort to make 2D more convenient. Which is good for me, because I was starting to hike out of area for 2D movies.
But as for why Dredd is failing at the box office, it has long been my cynical opinion that the greater masses simply don't like good movies. They'll flock to see Twilight, Abrams Trek, Transformers, but give them something of quality and substance and they don't want anything to do with it. Of course, this thinking conveniently ignores all the good movies that have been out that have brought in decent money.
Another possibility if you want to be simplistic is that there were no real recognizable actors in the movie. I imagine conversations went like this:
"What about Dredd?"
"I don't know. Who's in it?"
"Some guy named Karl Urban."
"I don't know."
"Wasn't he in Star Wars or something?"
"You know what, this one's got the girl from The Hunger Games, let's go see that."
Again, a weak argument that can be easily proven wrong, but I'm sure there's a contributing factor.
Like you say, September is a slow time for movies, indeed in my area the theatres are only open during the evenings now, and there isn't much of a crowd.
And finally, it's possible the Stallone movie may have tarnished the reputation of the Judge Dredd franchise, even seventeen years later.