The 670 is to this generation what the 560 Ti was to last. The 670 has been the out and out price / performance leader with more than double the sales .... 2.5+ times that of any AMD 7xxx card on the market ..... and that despite the AMD cards being out as much as 4 times as long. Lotta talk of late about AMD's new driver performance but for whatever reason, the Techpowerup reference quoted compares AMD cards using new drivers with nVidia cards with drivers that are two generations old.
I'm reserving judgement till I see a comparison where both use current drivers but with major brand factory overclocked 670's available as low as $313 - MSI N670GTX-PM2D2GD5/OC with the corresponding 7970 from MSI R7970-2PMD3GD5/OC at $405, the 7970 would have to be 34% faster to give the same bang for the buck when costing $92 more. It's not.
http://www.techpowerup.com/reviews/AMD/Catalyst_12.11_Performance/23.html
With both cards using older drivers....the 670 was 4% faster overall than the 7970 at 1920 x 1200. With the new Catalyst drivers on the 7970 and the two generations old drivers on the 670, the 7970 is 3% faster. So ignoring for the moment that the test used new AMD drivers and 2 generations old nVidia drivers, we have a 3% performance advantage costing us whopping 34% more putting the price / performance ration clearly in nVidia's hands....each 1% performance improvement is costing us roughly 10% increase in price.
Even the cheapest "off brand" 7970 (from HIS) card is 18% more....that's way too much for a 3% performance advantage and that's *if* that advantage holds up when new drivers from nVidia are used in the comparison.
At 1920 x 1200, I'd grab the factory OC'd MSI 670 in a heartbeat
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127675
$370 - 10% off w/ promo code HARDOCP11X8G, ends 11/13 - $20 MIR = $313
On the other hand, if ya find the 4 games (FarCry3, HitMan, Sleeping Dogs, Medal of Honor WarFighter Limited Edition) are not already in your collection and you were gonna buy them anyway, it might be worth the extra $92 to spring for the 7970. The other consideration is that if playing at 2560 x 1600, the 7970 is a stronger card than the 670 at that resolution.....whether it's $92 better is up to you.