My comments about the succubus come from personal use.  Many times in heroics has someone said "we need more CC just get out the succubus"  And every time the first few seconds go well then it breaks, the succubus gets turned inside out and something very big and very pissed comes looking for me.

Personally I wish they would just remove seduce and replace it with something more offense oriented so its not even an issue anymore.

As far as pvp goes, I've actually had some good use out of it in AV.  I'm a demo/destro build so I keep the succubus up for the shadow damage boost, and usually on passive, so some hunter takesa pot shot, and ends up all hearty and gets a crit shadowbolt down his throat, but I would never go out of my way to use it because its just to iffy.