AnandTech -- gave the GTX 680 a clear 5-20 percent edge against the HD 7970 in most recent games, with "wholly unexpected and completely stunning" leads as high as 28 percent in games like Battlefield 3 and Portal 2. The card even kept pace with the Radeon HD 6990 and GTX 590 -- not bad when you consider that those dual-GPU cards burn around 30-50 percent more watts. Overall, AnandTech says "this is by far the easiest recommendation we've been able to make for an NVIDIA flagship video card."
HotHardware -- showed that the new NVIDIA could only be beaten by dual-GPU cards in 3DMark11, had lower power consumption under load (and similar consumption at idle) compared to the 7970, and concluded the GTX 680 was "the fastest single-GPU based graphics card we have tested" and "another win for the consumer".
The Tech Report -- put the GTX 680 "just a couple of ticks" below the HD 7970 in its particular "99th Percentile Frame Time" test, due to higher frame latencies in some titles, but indicated that the $50 price advantage, lower power and quieter operation more than make up for it.
Hexus -- gives props to the GTX 680's "super-funky" GPU Boost technology "that helps keep the card working at near-maximum potential at all times", and also points out that the card readily overclocks to deliver a 15 percent lift above stock performance in Crysis 2, leaving the GTX 590 in a cloud of dust and the 7970 in quicksand. On the other hand, "AMD's not far behind" and "we eagerly wait to see what happens to Radeon HD 7970 and HD 7950 pricing in the next few weeks."
Hungry for more? You'll find equally glowing verdicts at the More Coverage links.
[Thanks to everyone who sent these links in.]