My wife and I visited Tacos Matamoros this past Saturday for the first time and we're really glad we did. We got there about 1 PM, the place was almost full, but the friendly waitress found us a table. She didn't speak any English, and my two years of high school Spanish (from long ago) didn't go far, but it didn't make any difference.
We had tacos and flautas, washed down with some Tecate beer we purchased at a store on the way to Matamoros. The really friendly waitresses gave us Styrofoam cups for the beer and took our empty cans away. My wife had the small tacos, chicken and al pastor, and I had the large, al pastor and spicy pork, and we split the flautas. We really enjoyed that food.
Almost everyone in the place seemed to be from Mexico (except us, of course). Lots of families as well. It felt very much like being in another country. We thoroughly enjoyed the experience.
One question for Matamoros veterans: do they serve crisp tacos, or only the soft-shell type? Either way, we'll definitely be back...