It's not the spec that is bad, it's just you have to be very good to use it correctly. If you play faceroll all the time you will lose as you rise up the brackets. If you don't faceroll correctly then your partner will die because you can't heal them well enough. If you get tunneled you have a short window to heal and your heals are small (i.e. use bandages, better use of your bubble, warlock crack is better then our heals).
However when you time everything perfectly you can pretty much kill anything but a mistweaver or resto form druid in about 3-4 GCDS. I'm not sure but I think this is what GC has planned for all the other classes. He said we are the Baseline.
Yeah so Ret makes good players really shine but also makes Bad players look well...really really bad.