I've had Five Guys a couple times and it is pretty good for what it is. My "problem" with them is on the value equation. I find it only A LITTLE better than the fast food burgers but it is significantly more expensive (especially if you pay attention to the value choices at the fast food joints).

In contrast, In 'n Out is only slightly more expensive (if at all) from its competition, and the food is significantly better. Just a much better value, IMHO.