Hardly installed, one can not help but to launch a slew of tests and demos, the gain compared to my old 570, yet still very good, is significant enough to delight the eyes (+ 120% about by game / demo )
Now it's my i7 2660k / HDD trays that has limited my perfs, the GTX 980 does what you ask her and she does it well.
Go on an example Unigine valley:
Render: Direct3D11
Fashion: 1920x1080 2xAA fullscreen
PresetCustom
QualityUltra
* GTX 570:
FPS: 40.8
Score: 1709
Min FPS: 22.1
Max FPS: 71.9
* GTX 980:
FPS:
91.1 (+ 123%)
Score:
3811
Min FPS:
23.1
Max FPS:
154.2
Rising perfs, declining consumption, how not to advise. I would have been perhaps less enthusiastic if I had come from a series 6 or 7 or ATI equivalent, as we must admit that from one generation to the next, the gains are never exponential.