On the one hand I want to know who the chef is, where he's worked possibly, definitely see images of the dishes, the full menu, wine list, pictures of the interior, etc..
On the other I'd just trust for a good rating by a few dozen people (who mention dining with kids preferably), couple of example dishes and prices.
I think you could combine these different use cases but I doubt you can make the ultimate tool that addresses both.
For a restaurant, more important than the information is the feeling. The style. The occasion that is evoked by the fonts, graphics, transitions, everything.
Best minimalist design would integrate some high-quality shots that define the ambiance of the erstaurant, show/tell about the chef / owner, and then link to other sites that had all of the admin data.
There are my $0.02 - enjoy.
What's the atmosphere like?
How's the food?
Can I afford this place?
How do I get there?
What do I need to do now that I have decided to eat there?2. location
3. opening hours
4. menu with prices
Might not be strictly necessary, depending on the restaurant:
5. some way of reserving a table (even if only a phone number)
(But "ultimate" =/= "minimal".)