I know, I probably haven't posted enough for my opinion to matter on this, but I figured I'd give it a shot. I'm not going to say too much, though. If you want to read a good, in-depth review of the preview, go visit Wow.com's Dawn Moore for the healy version of priests or Fox Van Allen if you're feeling a little darker.
Personally, I'm very intrigued by the new changes, especially all of those to smite/holy damaging abilities. While Smite spec still isn't quite viable, it's very very close. Not only that, I think it may be possible that a holy healing/holy smite hybrid build would work... kinda. Here is the build I came up with. If you consider all of the bonuses to smite (Evangelism, Chakra, Searing Light) that's a 44% bonus to damage! Not only that, a 20% extra chance to hit, meaning we wouldn't need hit in holy gear, and Atonement will allow for those chunky smites to heal while they damage. When you get tired of smiting? You can use Archangel to restore a little of your mana and increase your healing output for a few seconds. Now... let's do a little thinking... I've seen my smite now crit for 7k? I think. That's probably just me making up numbers, because I haven't smited in forever. But let's use it anyways... Say I do 7k with a smite. 44% more smite is 10k. That's a nice bit of damage, and if it crit, you can immediately normal smite with Surge of Light. Not only that, but, if you have Atonement, you heal a nearby raid member for around 4.5k. Now... that's not a huge amount, but it's a "smart" heal that immediately helps someone near the thing you're smiting (probably the tank if you're smiting the boss), and it's about the same as a Flash Heal for the cost of a smite. And that's just the current numbers that we see in Wrath.
Overall, I'm very impressed with the possibility of priests (i.e. ME!) being able to do a little damage with their healing. Not at the cost of healing poorly, but with good situational awareness and a little bit of luck, it may be possible.