I have read over a bazillion reviews now my conclusion is split in two parts:

Cons:

1080p gaming gives similar/close fps as 5870.
Eats quite a bit more than the 5870, you could have 5870 CF and still manage to save a few watts.

Pro:

AA performance seems good less of a hit.
In some games its performance is closer to 5970 than 5870, but then again 5870 CF would perform better than the 5970.

Result:

5870 2GB @ 900Mhz would close the gap with GTX 480 and it would be very close around 1080p. GTX 480 as it stands at $500 is very good card for the price. Lets see it its price does not go the way 5870 did and keeps stable at $500 "Its very hard tough"

If 5870 2GB @ 900Mhz is available around $420-$429 it would be a good alternative against the GTX 480 specially considering the less power consumption.

BTW 5870 was listed at $399 originally maybe at last AMD will offer 5870 at the release price