How important/good is slam in PvP?

[VincentVolaju]

I was wondering if slam isn't as good as I originally thought it was? I know it's used for interrupting spells / gates etc. which sounds like kind of a big deal on a PvP server, something you wouldn't want to give up if you had the ability to get it.

So with all the Iksar SKs running around / being rolled now, I was wondering if maybe it isn't all that great after all? Does it rarely land or stun maybe? Not very reliable?