I've been coming here for 15 years. Great food. Amazing tortillas. My co-workers didn't care as much for the salsa, but I love it. It has a little kick to it, but not too much, and although it's a runny salsa (as opposed to chunky), it has great flavor.
Have I had better Mexican food in my life? Yes. But Carolina's is a place that everyone should try once. It's an institution. I get the #13, which is an enchilada, taco, tostada, rice and beans. Awesome beans and rice. I suggest getting a chicken or beef enchilada rather than the standard cheese enchilada that comes with it.
The last thing I'll say is that a lot of people will look at the location and decide they're not going to go because it's in the middle of a neighborhood in downtown Phoenix. It is not dangerous. I'll rephrase that... It's no more dangerous than going to a chipotle in Gilbert. Cops and firefighters frequent the place, too, so don't let the location keep you from going.