AMD Radeon is releasing it's latest and greatest GPU on January 9, 2012. There is already many reviews out for it, and it's worth checking out more than one to get a good sense of how fast and powerful this $550 card really is.
But, in my humble opinion, this is probably the best review I've seen yet. It goes over the architecture in extreme detail but also makes it understandable, and then in the benchmarking they are extremely thorough. They are using a new way to represent GPU power that I have not seen anywhere else, where they actually record frame render times, which gives a good indication of any stutters you might experience in a game, even if you have a high average framerate.
Read it here: Tech Report's 7970 Review
Update: Jan 9/2012
Another awesome review featuring a ton of games as well as Crossfire performance:
TechPowerUp 7970 Crossfire Review