This is the best of the fast-foody-type Mexican places (like all the -bertos, Amado's, Vaqueros, et cetera), and in fact I say the only one worth even visiting. It's definitely authentic; not healthy by any stretch, but authentic. They do indeed make things like tortillas and masa right in front of you, and you can tell it's a small family operation as there's an older lady and I guess her older husband in there all the time (as opposed to the young brats who "run" most of the -bertos). If you're looking for a guilty pleasure, especially late at night, THIS is the place to go.
Also, I've been to other Salsita's around town and they're comparable, but not quite as good as this one. (On 32nd)