Sorry I really do not see it, I guess that retina display is blinding me! Really where is it please? Is it available if your system is in french?
OK just got my answer. Changed the language to english and it appears! I don't recall reading that it was an english only feature!!!?! I am not very happy customer, this was one of the reasons I bought an "new" iPad.
EDIT: I have switched back to french and now "Dictée" appears...that is odd. Now it works great.
So this is a trick for languages other than English: Switch to English, enable Dictation and then switch back to your language.
EDIT 2: just found that the french keyboard has the microphone for dictations, it is the French Canadian that does not have it...