gamer1357 :
I just upgraded from a 660ti, which performs very close to the 7950. I get about double the performance which is great, but I am also playing on 144hz. At 1080p 60hz I really dont see a large need to upgrade. AMD should be coming out with 20nm at the beginning of next year. You could wait until then to upgrade to either AMD or nvidia if they come out with a counterpart card or lower the prices of the current 900 series.
I usually decide to upgrade when my current card cant play the games I want at the resolution, frame rate, and detail I want. If it can do that now then dont upgrade. If it cannot, then go ahead and upgrade.
I have my 7950 OCd to 1150MHz, but find with high/max settings on some games (no or FXAA), that I can get dips to 40-45 FPS. Games like BF4 (multiplayer), ACIV, Watch Dogs, and obv Crysis 3. I'm just thinking might get worse with future games. Even with upcoming games like DA:I, AC:U, FC4, Witcher 3, etc.