I don't even bother with holy anymore in pve. I really don't see much of an advantage to circle of healing since the few nerfs its gotten, it just isn't that good anymore. I'm disc all the way. However I've got to say if you are considering a circle of healing spec... check out

http://www.wowhead.com/?talent#bVcbuhh0oZsEzcb0qi0hxzA

it seems bizarre at first but Ive run this build for a long time in pvp and the amount of spot healing and aoe in that build are just incredible.

Circle of Healing spam keeps surge of light up pretty much at all times giving you instant flash heals, not to mention inspiration for 10% reduced physical damage.

The big selling point though is keeping Soul Warding. Zero cooldown power word: shield is just OP.

You can basically just spam your instants with this build and it makes group damage disappear