As a Shadow Priest I am really looking forward to buff stacking being fixed, to level out the playing field a little bit. I will never be Top DPS, but some classes' numbers are just insanely bloated.
An example from Sha of Anger:
407k DPS? Really? Bare in mind a lot of the one's in the raid were not insanely geared, hence why they were doing Sha. I realize my numbers are bloated too, but in instances, especially 25 mans, some of the DPS put out by other classes is just incredible. The content is not even tweaked to compensate for the excessive DPS.