Coal burger is decent. A solid burger experience. The flavor of their burgers is good, and I like that they use grass-fed beef. They pay attention to the details too: fresh buns, homemade "special sauce." You won't leave feeling hungry--especially if you order a double. They don't have Coke or Pepsi, opting instead for a different, non-corn-syrup brand. Noble and unique.
Downsides? Well, the sides for one. I'm not a fan of their fries. They taste like they come frozen in a bag. Would really love to see some fresh-cut french fries here. Or, if they are freshly cut in-house, I wish they tasted like it. They're bland--the sort you'd get on the side of a burger you ordered at one of those national family restaurant chains. Not the worst things in the world, but certainly not on par with the quality of the burgers.
Also, it's a bit expensive--just slightly. I can think of at least 2 equally tasty but less expensive burger experiences within a mile of this place. So, although I think Coal Burger has a nice product, it isn't really a go-to burger joint for me.