I've been going to Five Guys since they first opened in Northern VA. I used to live about a mile from the original location. Coincidentally, I now work about a block from the original location which is now a "payday lending" shop..
My take on their product is that I love the burgers. Despite comments to the contrary in this thread, I've found the quality of the food to be generally consistent from one location to another, at least in VA. On the other hand I don't care very much for the fries. They give you a huge portion, dumped into the bag, but they are greasy, and become limp before you can eat more than a few.
I don't eat at Five Guys as much these days since the local (Herndon VA) store closed, but get in the mood for one every couple of months or so.