The net-net of my opinion/advice is this: If you have time to run a lot of instances and will want to heal them on a regular basis, go resto. Otherwise stay feral.
Here's the long-winded wall 'o text if you're interested.
I leveled feral through 70, and love it so have never really considered going resto. (With my main anyway...leveling a balance drood on another server for the different experience, and will go resto with her eventually.)
The cool thing about being feral is you can heal very well up to end-game with a healing set, in addition to having awesome DPS and being an excellent tank. I've assembled a set with like +850 healing just by grabbing relevant quest rewards when there was no feral option or a negligible upgrade, the occasional drop (including my Essence Focuser, w00t), and checking the AH for bargains. Meanwhile I have 2100 attack power in cat and 21,000 armor in bear. And I'm a casual player, with no PvP rewards and only a few pieces of instance loot. Please, hold your applause.
Note that as feral you can main heal instances, and I've done it successfully a few times, but at least for me the lack of talent-based "Uh-Oh!" abilities like Swiftmend and Nature's Swiftness makes it difficult and frustrating. I personally love healing the 5-man quests to take down non-dungeon bosses--they're hard enough to satisfy my occasional healing bug and make a good name for druid healing, but much faster and easier than trying to heal a full party for 2-3 hours through countless 4-mob pulls and multiple bosses. Gak. Then again, I've never played a healer so it might just be that I suck at it.
Feral is the better soloing spec, I'd say, with the versatility to down mobs lickety-split as cat, pop into bear to weather rough storms, self-heal as necessary, and get through it all with minimal OOM downtime. Restos are supposedly close to unkillable, but it takes 'em a lot longer to kill stuff on their own. Feral makes LFG as easy as you can imagine...once a group is coming together you can say things like "LF Healer -OR- Tank for _________." I love that. : )