Would love a different animation when in shadow form. Preferrably, one that would still be visible in shadowform without being all holyglow-ish. But that's not likely to happen (they aren't making druid animations visible in different forms, are they?).
That said, I generally dislike priest challenge mode set. It's fine on its own, but it's really bleak compared to others so far previewed. Paladin set is spectacular, druid set animation is awesome. Might be the case of 'grass is greener on the other side' but so far I only find priest and hunter sets to be 'meh'.