The food at Lopez is good, but it's not so spectacular to warrant the price. The drinks (including margaritas) are expensive, and the margaritas aren't really that great. However, if you go Sunday through Friday between 5-7 p.m., all the drinks with tequila (including margaritas!) are 50% off.
The fish tacos are a good bet, and the salads (oddly) are quite good, since they fry up some cheese to throw on there. Yum.
I also suggest the lobster enchiladas; they throw in shrimp and finish things with pretty good cheese and chipotle crema.