I have been going to Compadres for the past 4 or 5 years. Fortunately, they are about ten minutes from my work, so I am able to go there often for lunch.
The food is very tasty. I have not been to Mexico so i won't pretend that I can attest to whether or not it is "authentic Mexican." But I can speak authoritatively as a fat guy with experience eating at many Mexican restaurants when I say that Compadres is the best Mexican place in Lake County.
I have taken many co-workers here for lunch and meet my wife and kids here from time to time as well. My four year old, who won't eat anything voluntarily, sits right down and tears up five tacos on Taco Tuesday.
My favorite dish is chori-pollo. This is a grilled chicken breast smothered in chorizo sausage and melted queso fresco, served with an amazingly fluffy rice, refried beans and tortillas. The servers are so attentive that they normally know my order before I sit down. Very friendly staff.
The only knock I have on them is the chips and salsa can be inconsistent. Sometimes the chips are totes awesome, sometimes they taste like the fryer oil needs changed. The salsa seems to be varying degrees of spiciness (all good!) depending on the day.
Highly recommend this place. Muy delicioso.