As a meat eater: I had "the priest" burger. The burger patty itself was not that spectacular. It was a "slightly better than your first attempt" homemade burger. I came here expecting to be wowed by the quality of the burger meat itself, but it was overshadowed by the "option"...
If you're a vegetarian: Then you want to try this place! The "option" which is this fried, cheesy portabello mushroom patty is delicious. It is really deep fried though.
I added "smoke" to my burger which were fried jalapeno peppers. Pass it up, it just added some extra fried crunchiness and raw jalapeno flavour. I suppose I'd have preferred a more pickled flavour to complement the patty. It just stood out as a random flavour in my burger.
There was nothing special with the mayo or anything. No tasty spices or extra touches in the burger. It was just good quality meat. A good burger. Nothing to write home about. If you're vegetarian, check out the "option". That's all I can say.