I used this board for recommendations, and have never posted before.
Here is what I found in South Padre recently on vacation. Background, I used to live in both Corpus Christi and in Austin and am very fond of TexMex.
I was disappointed in Los Asados. I wanted Carne Guisada and it was tough and chewy. Chicken enchiladas were OK, mostly boring. Good service and it was busy, even at 1:00 pm.
Marcello's was OK, just OK. Lost Galleon was "always a wait when Winter Texans are here" but one night it was not that busy. Fried seafood was OK, better than average, not great.
Progresso was indeed easy to get to, clean, small. If I had it to do again I would have eaten from the street vendors rather than Pitayo's - but that's just me.
All in all, I was very surprised at the mediocrity of TexMex down on the border, in spite of the warnings here.