Tried a Five Guys cheeseburger when I was in Silver Spring MD a couple of weeks ago. Had absolutely no clue going in about this place whatsoever - I thought it was a local burger joint and it didn't dawn on me until I got in there that it was a chain. The reviews plastered all over the walls raved about the burgers so I figured it had to be good.
On the plus side the crew was friendly and I liked the ability to custom order a wide variety of toppings for the burger. The free peanuts were another nice touch while you are waiting for your food.
To be honest I didn't care for my cheeseburger very much and I did not finish it. The meat itself was somewhat lacking in flavor which surprised me given the high grease factor. And I like my fries crispy, which these were not.
Granted I'm a fan of In-And-Out (there is one only 10 minutes from the house). I think what separates the two, at least for me, is the flavor of the meat. And I think In-And-Out fries are also too limp most of the time, so the fry factor isn't a differentiating factor for me.
Next time I'm back east I'll give Five Guys another try, perhaps the hot dogs are better.