Meh, seems like a powerful UU choice for a tank with access to Mega Launcher and moves like Dark Pulse, Dragon Pulse and Water Pulse (not sure if stronger than Surf with that ability?), if you maximise its HP and SpA it could become quite the threat. It's obviously not gonna cut it in Standard - the OU metagame requires more than just good bulk and firepower (just ask Snorlax or Zapdos) - but in UU it could be a worthy tank that has the bulk to brush off resisted and weaker neutral hits along with the firepower to heavily damage its checks, unlike its bulkier competitors such as Suicune.
I don't think anybody could call it a bad Pokemon by any means, but all in all its nothing particularly outstanding, despite its massive Special Attack stat. It's just offensively and defensively outclassed by Mega Blastoise, Keldeo and (if it is allowed in OU now that rain is nerfed) Manaphy, the former having better all-round stats and rapid spin, the second having its near-unresisted STABs and massive power, and latter having superior bulk and Tail Glow.