Not too worried, having bought a 780 recently. Obviously these are much cheaper, but if the higher power draw, load temps and noise are anything to go by, the R9 290X isn't going to be a complete 780-slayer (even if it will probably take the crown in a handful of titles that are AMD favoured).
I moved from a 5870, which has given me 4 years of awesomeness, but it doesn't look at first glance as though AMD will pull out another '5870' moment with this series. And if they do, ho hum - the 780 is still a great card!
I hope there is good competition at the top end though, it's been a while since AMD was up there...