This is a relatively new place on Rt 193 near Beltway Plaza (on the eastbound side, west of the mall, more or less across from Siri's, in the location of the long-gone Dunkin Donuts).
The tacos de barbacoa are outstanding, juicy with a real depth of flavor. Asado is very good. Tacos al pastor and tacos de lengua have both been decent. Several other items have been hit or miss (a ham torta, in particular, was a miss), but I haven't scratched too deep on the menu, mostly the tacos. I'd currently rank this place above the Beltway Plaza incarnation of Taqueria Tres Reyes. I'm not sure it's necessarily better than any of the Kenilworth/Edmonston places, but if you're nearby, it's decent enough to skip the ten-minute drive down there.
I don't think any of these top the tacos I've had at TECC (in particular, the chorizo), but if you're in PG County, this is a more-than-respectable substitute for the long schlep to Arlington.