I seem to have practically unlimited mana. And my gear isn't even that 'pro'. I'm not sure if holy can use it more than disc, but that too doesn't seem that starved for mana.
The haste buf it gives doesn't seem that critically important either. It seems like the talent could use another more potent buf, unless level 100 is more mana starved.
Also Spirit Shell is technically weaker now since it can't be forced to crit on the first go, though I guess PoH in general is weaker in the future since no 10man hc.
I generally think Holy is a much stronger and interesting spec now. I'm not sure I see the appeal of this approach. I generally love changes more than anyone but they oversimplified.