I really loved the healing style back in BT/Hyjal, I liked the Tree form, and more importantly the spirit buff and the group synergy that went with that.
For those newer druids - back in TBC while in Tree of Life form everyone in your group got a percentage of your spirit as +healing done to the group.
My role in raids was as a tank healer, my gear was stacked with spirit (I often forwent set bonus' and wore a lot of cloth to increase my spirit - before the leather specialisation bonus we get now) and I was in the tank group with the 3-4 tanks. Healing wise my favourite fights were the multi tank fights, namely Bloodboil, I'd keep lifebloom and rejuv rolling on all 3 tanks, adding in Regrowth or random raid rejuves in any spare GCDs I had going - because of the stacked spirit I never ran out of mana, and the fact I was primarily healing the tanks I was grouped with made up for the lack of spell power I sometimes had.
I didn't mind the fact we were limited on what spells we could cast, because I only wanted to cast my HoTs anyway - naturally I had my NS+HT macro for 'oh shit' moments, as well as tranquility.
I think the only more recent spell I'd really add in would be Wild Growth and the AoE on Swiftmend (which I don't think we had back then?)
Obviously I'd have to change the mastery to suit, as harmony's buffing of the Direct Heals wouldn't be much use, possibly mastery could increase the spirit to +healing buff
TBH I've yet to really play my resto druid in MoP, so it might be a bit better now, he's pretty much always been my main, until mop at least, but the last 2 expansions I've not really enjoyed healing as a Druid anywhere near as much as I did in TBC...