After the very successful launch of Nvidia's GTX 970 and 980 graphic cards, AMD has made the executive decision to slash prices to keep up the competition. With Nvidia's new maxwell architecture, 900 series cards perform better with lower power consumption, heat, and lower core and boost clock. With skyrocketing sales and much lower prices to AMD's R9 series cards, cutting the prices was seen as the only way to keep up with sales and not fall too much behind in the competition. Even with higher prices of AMD's cards, the 970 and 980 have beat almost all benchmarks against AMD's cards and with new drivers on the way, that margin is expected to increase even more.
As an owner of a Asus Strix GTX 970, I can say myself that these statements are true and there is no reason to buy an AMD series card unless you're going for an all AMD build. Because of such a low price to performance ratio, these new cards are a true bang for the buck. At a price of $330, you're getting GTX 780ti speeds at half the cost and better power consumption and heat output. If you're looking for a mid range budget, but high end performance card, I definitely recommend these new cards.