The most important thing to say about the new Radeon R9 290X 4GB is that on the price performance scale it's a clear winner against Nvidia's GTX 780 3GB, at the time of writing. It undercuts it by at least £50 in the UK and $100 stateside, yet outperforms it almost universally. In doing so, it makes GTX Titan look even worse value than the GTX 780 3GB already does.
Compared with other AMD cards, it's value isn't quite as good, however. For example, while its performance is a huge jump over the R9 280X 3GB (up to 40 percent in some tests), it's also double the price of it. Sadly, diminishing returns are to be expected with the highest end cards. We've also seen some very good deals on the HD 7990 6GB recently as well, although whether or not a dual GPU card is for you is another story. These cards also lack the TrueAudio DSP that the R9 290 series features, although this is mostly an unproven technology for now.
The card is a decent enough overclocker, although the Overdrive interface certainly needs some work. That said, it shouldn't be long before better third party overclocking utilities fully support the card's new approach to overclocking.
There are certainly valid concerns to be had about the card's power draw and efficiency, and if this is a top priority for you you'll likely want to look elsewhere. As for the temperatures, we're cautiously willing to take AMD's word for it about the card being safe to run at 95°C. After all, if it weren't, then the company would be expecting a whole stack of dead GPUs within a few months. Nevertheless, there's no denying that this is one hot running GPU, and this will certainly have an impact on ambient case temperatures, which is something to consider. Hopefully, though, it will encourage board partners to come up with cooling solutions that let the card run at its maximum potential while still keeping things cool and whisper quiet. Indeed we rather suspect there's ample headroom in this regard, given AMD's relatively simple cooler.
There's a large price/performance gap between this card and the R9 280X 3GB that will be imminently filled by the R9 290, although how well remains to be seen. Meanwhile, Nvidia has little option now but to respond with price cuts for the GTX 780 3GB, which makes all the more sense given the also imminent release of the GTX 780 Ti. Therefore, the market could very easily look rather different in two or three weeks, so the best option may well be to hold out a little while until everyone knows where they stand. However, the long story short is that if you're after a high performance single GPU card, the R9 290X 4GB is the best deal currently available.