The concept is great when it works, but it often fails to work.
1) Sluggish staff and overall a very slow operation. Almost always under-staffed.
2) Most of the times the store would be out of at least one / two key ingredients, and the staff would substitute it with something cheap without notice, and the (borderline outrageous) price tag stays the same.
3) Under trained staff - I always see them looking up on the board, ingredient by ingredient, and putting those into the blender. I don't see this as a huge problem, but it does result into inconsistent tastes for the same order.
I have seen similar reviews on Yelp about the same store for last 2-3 years, and the store support personnel has also responded to the reviews. How is it that literally nothing has improved?