Yes, they use free range grass fed beef, and no, you won't be able to tell the difference, unless you are part chupacabra, but in that case you don't need to be paying for a burger. The important thing here is that you're doing something that will supposedly help the environment.
The burgers are great (on par with Mighty Fine, which I find to be incredible), but they also give you a huge range of topping options here, including spicy relish, carmelized onions, etc. The burgers were tough to eat - sloppy and really moist, but otherwise no problems there (make sure you grab plenty of extra napkins). I got the double burger based upon the reviews stating that the patties were really small, and I couldn't finish it. Once again, I think that the patties are the same size as Mighty Fine. A single and fries would probably suit most people fine. They have a single combo for $6.99.
The fries are other worldly. Super crispy and really nice olive oil flavor to them - nice and salty too. The order of fries is pretty big too, so you may want to consider sharing an order between two. A lot of people were complaining about the fries being soggy, and as mentioned, we didn't have that isue. If you do, I'd suggest you ask for some fresh ones - not that hard, eh?