My toon is only 38 right now but looking at the spells to come, I have to say that I'm a bit distressed at what appears to be a lack of variety of healing options for us - my shadow priest has his SHIFT2 bar nearly completely full of healing spells and he's only 71 but from the looks of things, I'm only going to have maybe half that as a healadin - I take it our healing rotation is pretty simple then?
INT as primary stat - NP, pretty much a given for any caster.
Looks like there's a bit of a debate between haste and spirit though - lots of fast little heals combined with taking advantage of our freebies vs good regen and some of the bigger but slower heals I take it?
Right. The theory is that more regen actually is more throughput if it allows you to convert Holy Lights to Divine Lights/Flash of Lights (whereas if you're chain-casting DL anyway, the only way to get more water through the hose is haste). Spirit will be more important with the new spell costs in 4.2, since Blizzard is continuing to try to make mana considerations more important, even in groups where you aren't compensating for the raid healers. And the mastery changes /might/ mean that while you don't seek it out, maybe you don't automatically reforge it away, either.
As for rotation, I personally find that the complexity comes from HP management, cooldown management and long-term throughput/mana balancing (including DP usage) rather than GCD-to-GCD spell choice. So it's probably for the good that we have only two real rotational spells, one filler, and one real HP finisher (YMMV in 25-mans). And even with that said, I don't use, say, Aura Mastery, as much as I should. I suspect the toolbox is of similar size as that of other classes, just broken out differently.