I've been eating at Carlos O'Briens off and on for over a decade now. In that time their menu hasn't changed much, and ultimately that's a good thing. It's a restaurant that is realistic about what they are. You won't find a lot of authenticity here, but you will find consistently decent American-style Mexican food. And that's just fine.
I'd normally rate them four stars, but they've had a bad run the last year or so. Still decent, but not up to their normal standards. Their best dish is probably the Pollo Fundido which is rich and delicious. I'm also a fan of their Papa Fajita which is a reasonably healthy option if you order it without the cheese.
Their chips and salsa are always good and the service is consistent, friendly and always good. A low point is their soda mixes which are hit and miss.
Overall a decent place to grab a decent meal, but a place that could be a lot better with a little more effort.