What 'Elements' -make a great level?

[thinker]

If you have a very difficult level designed: as you probably know, the player probably has to start over and over again. It would be a good idea to NOT have to go through a boring phase of the level over and over again. Or, It doesn't take too long to get to a difficult area. You don't have a difficult puzzling situation at the very end where the player has to go throught the whole level -just to get to the problem again- especially, if most of the level is boring!, tedious, or one of the kind where the player has to guess at the right path, almost at every turn or junction, etc. Ian Wilson (thinker)