It is surprising no ones popped up with a "woo, look at my benchmarks" thread with one yet, really no matter how poor value a card is SOMEONE normally buys one. Even Nvidia fans aren't getting on board. Though, I don't recall, has anyone on these forums owned up to spending something like £1000 on one of those ridiculous Asus Ares cards, there is a limit it seems.
I think for AMD/Nvidia its also largely down to the timing of the cards, released 3 months ago they'd be far more interesting, but most of the people that REALLY want that level of power would have gone sli/xfire a couple months ago. Thats where the 4870x2 did so well as it was released almost straight away, mostly the same for the 5970 though less good value. These two cards are less good value, more problematic(heat, noise, blowing up) and really late.
I mean a 4870x2 got a good 14 months or so before the 5870 launched, the 5970 had around a year, these cards will have 6 months, maybe 7, so in those terms its less good value as they will be the best cards around for a lot less long, and due to price they'll also depreciate much worse when it comes to selling on.