It isn’t about the fact that it has twice the performance of Titan X, but the price is way lower than that of Titan X. Titan X is around 1000USD but GTX 1080 is aroun 600-700 USD. Given the performance, I’d say it is a big leap. HotHardware made a review and also presents the full specs of GTX 1080 and it seems that it is the best thing in the market right now.
Extreme Tech has also a very positive review of the video card.
Given the performance and price, I’d say that my dream gaming pc will or might use an Nvidia card now.
The YouTube reviewers out there all say, in one voice, that this card is za best.