Personally, I agree that Kyurem-W is better, but they're not very comparable due to being on opposite sides of the attacking spectrum- and even then you'll need a better reason than that to bring something down from Ubers.
As for my opinion on the topic, if it had Ice STAB I might've actually been afraid of it, but really, all it has is Dragon a single non-STAB Electric move, and a relatively low speed. The lack of Earthquake really hurts especially when Reshiram gets both Earthquake and Earth Power hahahaha and Ice is a pitiful defensive type- echoing Slant, the fact that it's weak to the two most common priority moves is a pretty big killer. Stealth Rock as well, though personally I don't run it on a few teams, would probably murder it due to most sets being choiced and required to switch in and out unless you're at the point where it'll just sweep with Outrage or something. The typing really lets it down, doubly so because it carries the weaknesses of the ice type, but none of the strengths.
tl;dr it's not something I'd be particularly afraid of- though I don't battle much and actually never on the ladder so idk