Well we all know the ps4's gpu (1.84 tflops) is a bit better than a 7850 (1.76 Tflops) and the hd 7790 is overclocked in the x1. So you can easily compare them on benchmarks.
As you can see the differences are not that great. However this hd 7790 packs gddr5. The x1 packs drr3. The x1 should be able to counter this with the esram.
A game like thief has showed us that , x1 runs at 900p en ps4 at 1080 both at 30fps. So what the x1 does is lower the resolution to 900 p to get the same framerates the ps4 has BUT the x1 has reserved 10 percent of the gpu for the kinect. They now lowered that to 2 percent. So they probably can do 1000p or 960p which makes the differences small.
Maybe you haven't noticed it but the gtx 480 that hangs around the ps4's gpu, is almost 5 years old.
Having said that, both are hanging on the bottom of the gpu list and these benchmarks are a year old too. Better graphics cards are already on the market and for 300$ you have a graphics card that doubles the ps4 gpu in performance. In 2 years time this will be low end graphics.
Let's not talk about the cpu, that ps4's power was already midrange 6 years ago. These are the weakest consoles that have been released in hardware history.
Anyone who buys them , makes a bad investment when you look at hardware. Especially when you can have a full flegded pc for a 100$ more that beats the ps4 and has complete controller support and is plug & play. When you upgrade it later on (with the gpu only because the cpu will already be double the power, now!) it's gonna be like a gen of difference.
The kinect can play a big part in vr though, and you can use the console for your fighting & family games. Nintendo however is working on a new console and rumours are it's a beast.