Toms Hardware has their massive 20 page review online talking about everything you ever wanted to know about the new Fermi GeForce cards, and ends up breaking it down into 3 main things: The Good, the Bad, and the Ugly.  The cliff notes (reduced for size):

First, the good—performance. Fortunately for Nvidia, it had a few targets in the Radeon HD 5970, 5870, and 5850 as it was generating specs. While we’re sure the company wishes it was shipping 512-shader cards instead of pared-down boards, it’s hitting high-enough clocks to make GeForce GTX 480 and GeForce GTX 470 generally-faster than Radeon HD 5870 and Radeon HD 5850. (…)

What about the bad? Well, getting your feet in the door here costs $350. A flagship GeForce GTX 480 runs $500. Radeon HD 5850s recently dropped back down to $300 and Radeon HD 5870s can be found around $400. Though the GeForce cards are faster than their single-GPU competition, the premium is hard to swallow if power and display connectivity are important to you, and less-so if PhysX, CUDA, or 3D Vision are more interesting. Do we expect AMD to drop its prices in response? Don’t count on it.  (…)

Then there’s the ugly: power. Nvidia argues that the enthusiast space isn’t as sensitive to figures like power consumption, and that lofty load figures still only translate to a few dollars per year. (…)  Of course, that power invariably gets dissipated as heat, and thus the GTX 480, in particular, becomes a very hot card, cresting 160 degrees Fahrenheit on its surface during game play.

Be sure to go read the full review for all the details.