When i first read about this spell i thought it sounded great, and i still think it sounds great.
But now i'm getting to use it i'm finding it's not as fun as i hoped. It doesn't seem to fit very comfortably into our rotation. It feels more of a pain to put it down with the cast time, if it was an instance cast it might feel more usable.
I'm finding while im learning boss fights im having to move alot and i think in general the heroic boss fights invovle quite a bit of moving, so having to cast rune of power all the time when i come to a stand still, again doesn't feel very good. Even heading back to your rune can waste time as other classes can dive right back into dpsing, were wondering back to our rune or recasting another which you may have to move from before too long.
I'm trying not to make this a moan, as i'm more curious how people are using it or if they think a different talent is more worth while. The buff alone seems to make this the clear choice but perhaps not.