After looking at the reviews the R9 295X2 looks like the best dual GPU card to date. It's a shame that it cost's so much.
There is actually a reason to get this, over just 2 R9 290X, its much cooler and quieter.
However, for the price, you could buy 2 R9 290X, and build a custom loop to cool them... and then they would be much faster, cooler and quieter.
Still, this looks awesome. Sadly, I don't think it will cause Nvidia fanboys to change their mind, considering for the price you can buy 2 780Ti's and whilst they are much louder, hotter and slower in certain cases, they will ignore that.