Mm.
I agree it suffers from the same problem as any other form of utilitarianism (i.e. what even is the utility function). Or indeed all forms of ethics, because for basically every topic there's at least two cultures who disagree with each other.
On the other hand, even as a toy model (something I can also say for all ethics), CEV seems like it might be a step in perhaps a useful direction: "When a user asks you do do something, first figure out what they actually meant to ask you if they were smarter, then do that instead" is better for the user than just "do the thing", though it still has problems with "what happens when the thing they want is illegal?"