The first reviews have dropped and it seems that we have a few interesting points to look at, even for the "rebrands".
The R9 390x managed to cut down on power consumption, even though we have higher clocked memory and higher stock clocks.
(source: Guru3d.com http://www.guru3d.com/articles_pages/msi_radeon_r9_390x_gaming_8g_oc_review,1.html)
This specific model runs at 1100MHz, 100MHz faster than the stock R9 290x. It has more memory and the memory is clocked higher as well, at an effective 6000MHz compared to the 5000MHz on the 290x. Yet power consumption is down by 25+W somehow. edit: These results don't seem to add up with the results form hardwarecanucks. They reviewed the TriX R9 390x and measured the system power consumption, and from their results the 390x consumes 5% more power, but is also 10-20% faster than a 290x. Which would, again, speak for some improvements when it comes to efficiency, but not quite the outstanding results that guru3d.com has published.
Performance is good across the board, in vendor neutral titles it's as fast as a 980, in Nvidia optimized titles it's a bit slower, in AMD optimized titles it's a bit faster. That is at 1440p. At 1080p the 980 gains a few %, at 4k and higher the 390x gains a few %. Doesn't really change the overall picture though.
Temps and noise seem very much under control for this specific model, and since we have nice coolers from the get-go I expect them to be good across the board. I'm still interested in the new stock cooler but I couldn't find any reviews for it so far.
Overclocking will, of course, also depend on your luck and the specific model you have, but it seems that another 100MHz on top of most factory OCed cards is possible. Giving the card another tiny bump of a few %. So overall it competes with a 980 and even beats it for 4k UHD gaming across most titles, at its promised pricepoint and with the slightly reduced power conumption it seems like a good deal to me, and 2 of them (or 2 R9 390s) would be ideal for a "cheapo" 4k setup.
R9 380, a huge disappointment in my opinion. Power consumption is nice and low at <200W, but it's effectively an R9 285. And that means that it's slower than a 280x in many cases. At least it is available in 4GB models from the start, and it is a decent midrange card, but I'd like to see a 380x honestly. I want to see what a larger Tonga chip could do.
R9 370, again, decent for the money but nothing spectacular. Basically an R9 270 performance-wise.
No Fury, FuryX or Fury Nano reviews as of now, we only have cherry-picked benchmarks from AMD to work with because someone broke the NDA on the reviewers guide. But they're supposed to be reviewed and "available" next week.