Seriously, I think it's just too soon.
In 30, 20, perhaps even 10 years from now, a movie like this will be important - to remind us what happened, to tell the stories of those who lived through it, and to honor the memory of those who didn't.
However today, 5 years later, there are still people who cannot leave their homes because of it, who cannot work because of it, cannot get on a train, or go into an elevator, or hear a plane fly overhead without feeling fear and panic ... because of it. I think it's too soon for a reminder.
There are 5 year old children who have never met a parent, nor could they possibly understand why - even I don't completely understand why myself. And I think it is wrong of Oliver Stone to exploit it, just as I think its been wrong for "W" to shove this day down our throats, using fear to keep us in line.
The recent threat that occured in the UK at Heathrow is enough to instantly take all of us back to that day. Reports about bombs on planes immediately frighten and immobilize us. Of course, any threat to us on American soil shakes our very faith in man and his capabilities.
Personally, I will not pay money to sit in a theatre for that same feeling, and relive something that we already live over day after day after day.