See my Mac wish list.
Yes, you want one. It looks fantastic in person, shot below from CES. But at present it works only on the 2016 MacBook Pro, via a Thunderbolt 3 cable, as shown below. OTOH, for about $1700 you can get a 5K display from Apple with a free computer.
I am NOT recommending it for work where evaluating image sharpness or very fine tweaks is needed—that’s why I still use the NEC PA302W for my image evaluation—the pixel density is way too high for that type of detail work. But like the iMac 5K viewing experience, the LG 5K is aweseome for viewing images, with its 14.7 megapixel display.
I did not chance upon the Dell 8K 32-inch display which was announced at CES, but a 32-inch panel now exists, it seems ideal for an iMac 8K which could use a custom graphics solution to push those 32 megapixels. An 8K display requires the bandwidth of four 4K displays and isn’t going to fly with any Mac (yet).