It is mainly useful for an aura granting fast healing, that can be nicked with a feat
Highly debateable (and I'm obviously on the "no" side), but I don't want to start that argument for the bajillionth time.
I agree, let's not start that discussion.
Assume it cannot be nicked with the feat, even then his abilities are sub-par to a decently optimized bard. Healing the entire party can be done with cheap items/tricks anyway.
There are also a limited amount of options when playing a dragon shaman, dipping one level for an aura is probably pretty decent. But if you want to primarily play a Dragon Shaman, your multi-class options are very few and far between, and retricts themselves to dipping.
Also the other auras than healing grant +1 or 2 to some rolls, or a lousy energy resistance to one type of energy, everything something that is fairly useful in low level games, but at higher levels it is meaningless.
The class makes for a good Con Focused High AC Survival build, but a Crusader does that better while still being a threat.
My verdict is probably Low Tier 4 with unique auras, and High Tier 5 with non-unique auras.