I'm of the sad opinion that rune sets are smoke and mirrors. They boost one stat a great deal but there are usually 2-3 other stats they add that are useless. I would really like a rune set that does great things. I have a full set of the Mad King and the Summon Ravens to attack foes occurs when "activating" an elite. On almost every elite it summons them on "deactivation" of the elite (which I bug report about every 2-3 days) which is not when I need it or want it - and it is on the same cooldown as the elite. Really more smoke and mirrors than useful - imho.
And I find this the same with most "sets". I just prefer a continual boost to stat whether it is condition, toughness, power, or percision - or all. My Ranger (at 65) isn't using a set of runes and does a fantasitc amount of crits - and yes, I have a fetish about crits - I lie awake at night thinking about them - then after falling peacefully to sleep - dream about them and wake up in the morning needing to brush my teeth since the taste of crits is in my mouth. (OK - I would be brushing my teeth anyway). There is just something about seeing huge numbers roll by. I'm using some stone that gives +20 to percision, +14 to power, and + 14 to toughness and have armor that gives percision and condition damage. The point is that with six gems - I get +120 to percision, + 84 to both power and toughness for a total of 288 points added to stats. Most rune sets add a total of 165 points to just one stat. Anyway, that is my opinion but maybe I'm missing something.
At the moment I'm not buying into rune sets. And when I can afford some "uber" gems for my Necro I might just go that route especially since the summoning ravens is bugged - and I don't know if they will ever fix it.