Versus the R9 290X, the 290 has had only two minor adjustments: the peak clock speed is down from 1000MHz to 947MHz, and the number of active compute units on the chip has been reduced from 44 to 40. That means the 290 has a truly enormous amount of shader arithmetic power, but not quite the borderline terrifying capacity of the R9 290X. Both should be more than sufficient.
Now look at the other specs. The 290 retains the Hawaii GPU’s full complement of 64 pixels per clock of ROP throughput, so it has loads of pixel filling and antialiasing power, and it can still rasterize quad primitives per clock cycle for high-polygon tessellation goodness. Even better, the R9 290 has the exact same memory config as the 290X, with a 512-bit-wide path to four gigabytes of GDDR5 running at 5 GT/s. Memory bandwidth is oftentimes the limiting factor in graphics performance, so this choice is especially notable.
You can check out a comparison right here. The article says the 290 wasn’t originally this powerful; as the story goes, AMD was readying its next gen cards for release when Nvidia slashed prices on its cards, putting the GTX 770—which is the card the 290 was aimed to compete with—out of its price range and pitting it against the GTX 780, a faster card that Nvidia also bundled with three games and a $100 discount on the Nvidia Shield. AMD responded with a driver that matched the 290 up better against the 780, raising the max fan speed limit to 47% which gave it a few percentage points of performance.
Out of all of this the clear winner is the consumer, which I’m definitely okay with.