I'm very neutral to this. I don't think Holy is bad at all when there really is damage to heal, but I agree with Holy's mastery being poorly designed, and that it should be changed to something that prevents the huge amounts of overhealing.
Now, as I said that I think Holy is fine, apart from the Mastery, I also agree that it's really not fun to look bad on the meters (even when in reality you can't judge how good someone is, just by looking at the meters) and make everyone think that it's all you're good for, when you know you could do much better if you'd have a chance.
So yeah, Holy is really viable at the moment, but a little redesign to a couple of things wouldn't hurt us either!