No, it's not blurry. Read the Eurogamer article about how it works. It is not anymore blurry than a native 4K image.

EDIT: well, apparently in the Tomb Raider comparison above the PS4 Pro version is quite blurry lol
It is not supposed to be blurry with this checkerboard technique, but I'll be damned... blurry it is.

It is, even if you choose to ignore the differences:

The image is originally rendered with half the resolution of 4k. Then they fill the missing dots with their patented mathematical algorithm *cough* marketing bollocks *cough* to upscale the image on a 4k TV / Monitor. An upscalled image always tends to appear blurry.

http://www.red.com/learn/red-101/upscaled-1080P-vs-4K

Yes, I'm shocked that the difference is so big.

No, not always blurry. Some upscaling algorithms can avoid blurring, but at the expense of getting some other types of articfacts instead of course. And in Eurogamer's article it seemed as if Sony's "checkerboard" algorithm would be very good to avoid blur. Eurogamer made it sound almost revolutionary.

Apparently that's not the case lol

I wish PC graphics cards could do this tbh.

So big? First off looking at pics like that isnt a great way to make comparisons. But even if it were, let's face it.... in he real world who zooms in to look at their screen when playing games. In motion will we even notice that? 

And as for the "details".... I don't know why this happens, and it's probably what gets to me about these kinda arguments. When our Well in the know enthusiast PC folks make these arguments they have a way of developing some sort of selective knowledge that only highlights what point they are trying to make. How is it possible that none of them has mentioned that even if the PS4pro offers a rez bump, the "PS4" version of the game can still be using a lower resolution of textures compared to those used in a PC running g the ssme game at ultra. No matter how good a rez bump you have, lower rez textures will still not look as good as higher rez textures. 

It's one thing to be spitting marketing BS, it's another thing to customize a GPU and add components to it that allows the GPU do a specific task that GPUs typically don't have the hardware to do and patent the tech. 

And there is no doubt that an upscaled image is always gonna be blurrier than a native image. But the point is this;

It's one thing to upscale from 1080p yo 4k (that's making up for 6M absent pixels), it's another thing to upscale from 2*1080p to 4k. In that case you only have to account for 4M pixels. If the results are such that you have to freeze frame and zoom in to spot differences isn't that at the very least somewhat commendable?

And look at XB1 to PS4, 900p to 1080p.... it's already hard enough telling them apart as it is. When looking at 4k and faux4k it's gonna be even harder. 

Yes, that's what I meant by interpolate the non rendered squares using the rendered squares. But I also thought I had read something about temporal interpolation in the Eurogamer article. In static scenes the info from the previous frame can also be used.

Btw I doubt that Scorpio can do native 4K when the same game uses checkerboard 4K on ps4 pro. The ratio between pro and scorpio is about the same as between ps4 and One. Either the pro version will run smoother with more effects or the scorpio version will need to upscale somewhere too. The equivalent checkerboard 1080 is only 72% of 900p, or by the same ratio Checkerboard 4K and about 3264x1836 on Scorpio.

The Tomb Raider example's blurriness was due to Depth of Field blurring kicking in at a closer distance.
Which does speak to the over-all power of the system, but isn't related to the checkerboard upscaling itself.

Games just need to be coded to use this upscaling technique.  That applies to PS4 Pro as well, they need to use the technique.
I believe I saw a quote from developer Jonathan Blow saying that in fact it isn't 100% free in terms of GPU resources, it's just very efficient, and that depending on the game engine design being used, alot of the data needed to support the calculation will already be generated.

And while PS4 Pro currently has custom hardware which makes it more efficient to use this technique, I'm guessing that even without that hardware, it may still be worthwhile to use, as in more effective than trying to render 2x the number of pixels.   So it will probably show up in PC too.  AMD or even NVIDIA will probably make the fixed-function hardware available, and even those without said video cards could enable the technique if they wish.