IMNSHO it comes down to entertainment value and the fact there are two kinds of entertainment as far as demos go.
First of all, there's the audio/visual aspect. Lots of pretty visuals and slick music. Of course, most ordinary PC users are more than used to this from the current generation of games, which is why they may feel a demo like this is not that special (despite the fact the kkreiger engine's renderer is technically as advanced, or moreso, than many current game engines).
The second form of entertainment appeals only to coders and that's the appreciation of the technical feat and speculation on how various things were accomplished. Sure, it uses procedural textures that get generated on loading - but what sort of algorithms were used to generate them? How are the scenes described in such a small space?
3DMark may have scenes that are prettier to look at, but then it has megabytes and megabytes of images, models and animation data created by professional artists, fed into an engine that's designed to give a hardware shakedown and frankly little else (the reason it runs at 4-5 fps is because optimizing the code is not the aim of 3DMark, rather the aim is to utterly ravage your systems resources to derive a benchmark value).
Technically, there is relatively little to admire in comparison to a demo like this one.
