I stopped by La Unica based on the strong recommendations found here - and overall, it was worth it.
I placed a take-out order at the front desk - but the waiter was very slow writing down my order. I'm not kidding when I say it took him a minute-plus to write down what kind of burrito I wanted. It was a bit awkward standing there so long. Also, he missed a side (guacamole) but that is fine.
Regardless, the wait was not too long and I took my food back to my hotel across the street.
The ingredients were fresh and the taste was above average, however, the burrito was very soggy. I could not even lift it up to eat it - which made for a very messy meal.
The food was authentic and delicious - so I would definitely go again if I am in the area but be sure to try El Paraiso in Cornelius, as well.
FYI - they do not take AMEX.