As someone who had dabbled in this "social recommendations" space, finding reviews from friends when you do not have a big enough social graph is probably the b

As someone who had dabbled in this "social recommendations" space, finding reviews from friends when you do not have a big enough social graph is probably the biggest difficulty. Also, it may work in a place like SF, but outside of those deeply networked places, it becomes difficult to find restaurants with reviews on Yelp, forget finding places where your friends have been to. And remember that people are far more inclined to write reviews when they have had a negative experience, and not a positive one. A tough task. I wish you all the best.