"I see two types of buyers considering these cards.
First, there are the value-oriented enthusiasts who try to keep their systems updated once a year or so. They'd love the fastest technology, but know that flagships always carry the largest pricing premiums. These are the folks who kept an eye on our Best Graphics Cards for the Money column, and when Radeon HD 4870s hit $140 bucks, they bought (and got a killer deal, even by today's standards). If you belong to that group, are looking at "Radeon HD 5700-series" and expecting a big step up in performance, even the 5770 is a disappointment. After all, if you own a 4870 or 4890 already, that card is faster in today's games.
Of course, there's an X factor in play: ATI's value-adds. Eyefinity-the ability to run three concurrent display outputs-is completely unique at the high-end still. It's particularly exciting at the $159 and $129 price points being represented here. Likewise, the ability to bitstream Dolby TrueHD and DTS-HD MA are capabilities previously available through $200+ sound cards. Now you can get that functionality from a DirectX 11 graphics card. Both extras are compelling enough on their own to sell these cards to the folks able to exploit their benefits today. And it's personally telling that I've put one card in my desktop workstation to drive a trio of monitors, and one into my HTPC, driving a 55" Samsung LED display."