So far not terribly impressed with NVIDIA's graphs and presentation, granted they are skewed as always but in this situation it should be more clearly defined (2x performance is a bit of a misnomer as it is only for a very specific niche of the market, virtual reality). The embargo on reviews should be ending May 17th for the UK and May 21st for the US from what I've seen. Most Chinese and Taiwanese leaks show the 1080 edging out a GTX 980Ti by 15-18%. The 2x performance factor with virtual reality doesn't translate over to everything else it seems.
I believe there have been some questions surrounding the ASync computing of the generation as to whether it is truly hardware based or if it is just a modified API running off of the CUDA cores. We will see. Not many games are DX 12.1 and not many future releases yet so it is questionable as to whether NVIDIA decided to fake it until they make it like with Maxwell/old 5xxx series or not.