Are you trying to ascertain how much people like Sushi? Then you should ask "How much do you like Sushi" with a scale like:
A lot
A little
Not at all

Or even better: How would you rate sushi?:
Excellent
Very Good
Good
Fair
Poor
Very Poor

"Overrated" and "underrated" are relative to the rating of a thing. In order for your question to have any meaning, everyone's perception of how everyone else rates sushi would have to be the same. But if I'm answering the question assuming that other people rate Sushi as "Fair" and you're answering the poll assuming that other people rate sushi as "Very Good" then the results of the poll mean nothing.

Now, if you were to say "Assume the rating of sushi is 7 out of 10. Would you say that sushi is over/under/properly rated? That would be a valid question, although not very useful.