We've been to Frank and Fina's a few of times and have not been disappointed yet. We really like the food and service here - we always get a nice waiter. The ambience is also not bad either! Very clean and homey feeling and prices are reasonable in my opinion.
If you're watching what you eat, the roasted chicken with tortillas on the side is a good option (think El Pollo Loco, but better). I think I got two pieces one time and it was huge.
A favorite of ours is the carne asada torta. Awesome! The bread is nicely toasted and the guacamole is abundant. Their meats are good too. My kind of torta! The burrito is also good - be sure to get it enchilada style. The complimentary fresh chips and salsa is also a nice touch.
This Mexican fare is simple, but delicious. That coupled with good prices and a nice environment makes this a place we will visit again and again.