The reason spriest is difficult to master is because of the amount of planning that has to be done in the rotation to keep optimal DPS. You have to plan when to devouring plague such that your dots don't fall off on top of being able to refresh them both inside their last tick. All of this has to be done around our abysmal casting on the move capability. Through all this, you need to know when to snapshot regardless of length left.
If you ignore this, just keeping up dots, plagueing, and spamming mind blasts isn't hard, but you're dps will be weak.