Keep in mind I am no expert.
Out of the box, this is a very good card, capable of playing games like Crysis and GTAIV at 30fps, and games like Gears of War and Arkham Asylum at 60, a steady 50fps.
The card I recieved, however, is a non-reference model, which in short means (for me, at least) that the voltages cannot be modified or changed without physically modifying the board (soldering / pencil mod). This leaves (again, for me at least) very little overclocking potential. I am unable to overclock past 890mhz core clock without having games crash after a while. It's definately not an overheating problem. I am currently using a mediocre 600w PSU (OCZ) which have been criticised for being, well, not very good. I will shortly be getting a newer PSU (Corsair TX 650w) so hopefully I'll be able to edit this review and let the readers know if it was a PSU issue.
There have been problems with newer ATI cards having the 'grey screen of death'. This is apparently a driver issue and AMD are looking into it at the time of writing. I have personally been able temporarily fix this issue by underclocking the card to 855/950, which isn't a lot, but has seemed to fix the problem.
The card itself is quite large, about 9", so you're going to need a relatively big case, and it takes up 2 PCI slots (one for ventilation). It also requires 2 6-pin power adapters (converters come in with the card).
The card came with a few video adapters; DVI to VGA, DVI to HDMI, S-video, along with a copy of HAWX, which ironically won't work for whatever reason, and a door sign.
One last thing about this card: Disable the ATI audio drivers in device manager. At first unable to overclock at all, with GTAIV freezing immediately even if I bumped it up 10mhz. After I disabled the audio drivers, I was able to overclock, only then limited by the non-reference problem mentioned earlier.
All in all, this is a card worth having, and if you're not bothered about overclocking (which you wouldn't really need to do anyway), then go with the non-reference model. If you are looking to overclock, play it safe and get a reference model.