I actually think Ice Arceus is very underrated, mainly because of how much I love the Ice-typing in the Ubers. Offensively, I think it's even better typing that Dragon, since it hits so many walls for super effective damage instead of neutral. For example, Lugia can take a Dragon attack from Arceus, but cannot take Ice ones. Most of the good walls in Ubers are weak to Ice, namely Groudon, Giratina, Lugia, Ground Arceus. Ferrothorn gets hit for neutral (which is hard enough), and so does Dialga. Couple that with Thunder and something to hit Steels, it gets pretty hard to wall Ice Arceus without using Blissey. If it wasn't such a poor typing defensively, Ice Arceus could probably close to mid or even top tier, IMO.