No way, BZ4 is starting to like a Mystic Realm level?! =P
Anyways, what I like to see in a level is:
A: Challenging, but not cheap gameplay... I don't mind jumping over a pit, so long as the entire level is not jumping over a pit with little to jump from.
B: Unity, the level should not be a series of rooms. It should be a whole piece or at the very least split into only a few areas.
C: Consistent theme... Don't go from a desert into a jungle in the same level, make multiple levels.
D: Fresh theme, if I've seen it before, I'm more likely to be bored. The more different the theme of the level, and the accompanying gimmicks and detail, the more I'd want to explore it.
E: Balanced linearity is vital, because if I'm going to choose from a couple paths, I don't want to completely bypass half the level. Paths should meet periodically.
Finally a note too important to be assigned to a letter:
--Platforming, don't make it all gimmicks because it is the platforming that makes the game, and the gimmicks that sell it. Gimmicks can be cool, but don't overlook the classic run and jump.
However I still hold that I'll really only want to try something that has clearly had a deal of effort put into it. Even a beginner can make a decent map with enough effort.
As for Some Guy's maps, they often go a little heavy on the detail, but are typically pretty solid. Its nothing a few added barriers could fix in most situations anyways. VFZ is flat and the platforming in it is somewhat cheap or similarily boring, while I don't really hate it... I can see how it is not a model for good map-making.