Feelings I'm getting from different reviews:
- very erratic performance
- super fast in DX9 games
- no so fast in DX11 where tesselation is not overdone
- amazing tesselation performance, but a bit ahead of it's time I think
- too hot, power hungry and loud!
- very good compute, but I still wait for someone with Fermi to test OpenCL GPU raytracing app from this thread ->
SmallPT
So basing on that I'm very happy I bough my HD5870 at launch below MSRP (just by £10.00 but always :smile

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GTX480 will make sense if performance is your only consideration and you either keep rig in other room or watercool your GFX card.
I think refresh part will be very decent, but for now it's meh.
Unfortunately for nVidia in games I play or plan to play in near future GTX480 is within 5% of my card, but can OC on AIR only to ~800MHz core (+100MHz) where my Sapphire can do 1GHz+ with ease on default FAN profile (which means acceptable acoustic).