When I mean by hideously designed, I mean it looks like it was designed by a first-timer level creator who wanted to show off the world of his lol tough difficult level. It's ugly to look at, there's no semblance of any sort design elements aside from poorly stitched together levels with no cohesion whatsoever, and of course, all of the levels are strung together so the level is artificially long, with no checkpoints, and thus "challenging".
I mean, just look at it
*imgs*
I can design levels with loads of empty space and minimal platforms to make platforming challenging.
If you want a better comparison of a challenging platforming level done correctly, look no further than Rayman's Land of the Livid Dead levels. They're challenging, but also beautifully designed.