I'm updating and improving the review.
According to the proprietor, the cause of my last bad experience is gone, so I decided to return with some coworkers today. I was offered a free meal, but I declined it.
The service was much improved, efficient even. The food is very tasty. It is a taco experience that is quite a bit better than most Phoenix locations. A lot of their food tends to be on the spicy side, but not all. The house-made beverages (horchata and jamaica) are very good. The guac is chunky and very citrusy, which I approve of. Do not hesitate to check this place out, but be forewarned that parking can be challenging and the location is small and crowded. Nonetheless it has one-of-a-kind ambiance and outstanding Mexican food and drink.