For all of you Warlock beta testers out there, Ghostcrawler is looking for your help! Since the Wrath Beta began, Metamorphosis has been one of those abilities that sound cool in theory, but the application was totally wrong, more or less. Ghostcrawler has put out a call for focused, constructive feedback on the ability. When you head over there, keep in mind that Ghostcrawler wants feedback specifically about Metamorphosis in this thread, and 'get rid of it' isn't constructive feedback. Those of you not beta testing may be interested in the thread as well, since it might be a pretty strong indicator of where Demonology will end up.
The most common feedback I've seen is that the ability renders most of your other talent points null and void for the duration of the transformation, rather than synergizing with them. I find myself agreeing with that wholeheartedly. It's an interesting concept, but no top end talent should nullify everything before it unless it's good enough to make up for all of those talent points you lost. Metamorphosis definitely does not have 51 talent points baked into it, and I'd say it would be impossible to even do that.