At first I have to question how this can compete with places like Yelp, etc. (we have a dumber app here in NYC called menupages.com) but your use of Google Maps totally sold me.

I would suggest changing the language regarding accounts, specifically instead of 'login with openid' which some people may not have heard of, just have a register button. Also, definitely have an option for users to submit restaurant menu links to the restaurants they've reviewed.

Great job!