Cerberus has the second to only speed junctioning. And the other junction slots are alot more useful than pandemona's. Get him.

Cerberus allows you to kill a marlboro with <6 turns of magic use. (demi ad infinitum? and I rounded that for the 142k hp they have for 9999x3 for demi then other spells when demi falls behind xD $calc could always be wrong^_^)

But he can be more than useful if you use him right. I'd get him for the speed junctioning alone. not to mention auto-haste.