Control warrior guy swears by the Spectral guy, it is a really annoying minion to remove, a bunch of decks simply don't have good answers to it. Paladin can equality it but do you really want to equality a 5drop? Probably eats a peacekeeper right away and that's only on a 4attack minion so good deal regardless. Druid kinda needs to FoN it or have enough board to roar but they'll lose a bunch of stuff in the process, priest removal for such a mob is terrible you have to auchenai+circle then do 2more with nova or double spell pyro both of which are terrible, rogue more or less has to deadly poison and face tank it then play either blade flurry or fan+SI7 which is a lot of mana and cards. In comparison the drake rarely lasts more than the turn it's played on, so even though it cycles that's kinda meh.
Not sure you'd use it in priest, can't heal it so sounds a bit meh. Seems like a solid contender for Arcane drake, you don't cycle it but it sticks a lot better and is a nightmare for certain decks. This and Loatheb sure fills that cost issue nicely.