I haven't completed a heroic yet, but I have done a couple bosses from a few different ones, and to complete them (after a few wipes from figuring out the mechanics and a strategy) I've had to use the following spells;
-Prayer of Mending
-Prayer of Healing
-Hymn of Hope
-Holy Words (both Heal and PoM's Chakra's Holy Words)
-Light Well (actually being used now by DPS hurray!!!)
-Holy Nova (Great from breaking chains on the first boss in H BRC, and it tops people off!)
-Power Word: Shield (more to help people move out of aoe quicker than anything else)
-Leap of Faith (very situational, but very useful!)
I have never been happier, having to actually use all of these spells is awesome! Now I'm not saying I have been spamming these spells, the opposite in fact. But what I am trying to say is that I am making progress in learning the new system, and its already becoming easier for me to heal heroics with just a few upgrades!
The new system needs some polishing sure, but it is doable! I am by no means an amazing healer, I'd consider myself among the majority here, a casual. But I AM progressing.
I think people need to really give this new system a shot, coordinate your group. Plan pulls, plan fights, position properly, make mistakes and learn from them! This is all fresh content, instead of focusing on the negative aspects, try focusing on the fun that there is to be had.
Healing, in my opinion, is more fun than it has ever been. But its not just because of the new healing system...
Its because groups are having to work as a unit, even in 5 mans, to progress. Nobody is carrying anyone anymore, and we're all being given a chance to shine...
I don't know about the rest of you, but I intend to shine like a star!
PS: Cuddos to Blizzard, I love the new system!