Quite well, actually.
Channel 5's Gadget Show proved itself to be well up for the task of explaining 4K to a mass audience. They covered the fact that it's 4 times (and not 2 times) the resolution of HD, and - to their credit - said that they could see a very distinct improvement over HD (which is what we have always said!).
You get a glimpse of a Canon C500 here, attached to an AJA Ki Pro Quad recorder. Playback was from a Scan 3XS workstation with Nvidia graphics - this is the type of setup you need if you want to play back 4K in your living room right now!
We can't embed this, but here's a link (be prepared for about a minute's worth of ads at the start). It seems that the UK's Channel 5 only wants this video to be seen in certain territories. Appoligies if you can't see this in your region.