I saw the deal on the 7950 in Hot Deals and I was going to buy Bioshock Infinite and (probably) Crysis 3 anyway and I factored in that I could bump my bitcoin mining to ~550MH/s and sell my old 7850 for around $150 on Ebay so it seemed like a good deal.
I unboxed my new Sapphire 7950 and immediately found that it didn't fit in my case. The plastic cover of the Sapphire 7950 bumps into the hard drive cage of my Lian Li PC60. I should have measured it. The overlap was small, but if it doesn't fit, it doesn't fit. I looked at removing the plastic around the video card but the fans were attached. So I pulled the HD cage, relocated my drives around and put it all back together without the hard drive cage.
I fired up a couple of games and the 7950 card looks good - it's a small but noticeable improvement over my 7850. I had no issues with temperatures and the fans were quiet.
I overclock using MSI Afterburner.
My old 7850 overclocked amazingly - at stock voltage I had the core up from stock 860MHz to 1050MHz for half a year (22% overclock) - and I had been bitcoin mining at roughly 300MH/s with it with the temperature pegged at about 67C. I did the same thing with the 7950 and it overclocks well, but not as good as the 7850MHzl. The limit on my new 7950 is about 1100MHz core clock (19% overclock), 1450MHz memory clock.
And then back to bitcoin mining. At stock 925MHz, I get ~425MH/s at 68C with 54% fan. At 1100MHz core clock, I get ~520MH/s at 70C with 58% fan. I will say that I can feel the higher heat from the card though. It's been cool enough here in Colorado, so the extra heat is actually not a bad thing.. at least until Spring springs.
Overall, I'm pleased, although a bit bummed about the loss of the hard drive cage.