The food at Taqueria Guadalajara is at least as good as the Mexican food I got used to back when I lived in Northern California. I usually opt for their excellent tacos (try the delicious lengua de res [beef tongue]), but the sopes are also terrific.
The atmosphere is definitely homey and a little run down. I try to sit at the counter because I enjoy watching the action in the kitchen, but also because the back room where most of the tables are is a bit depressing and claustrophobic.
Another plus for Taqueria Guadalajara is the friendly and attentive staff. And the prices! I'm always way over-tipping here because I feel like I'm not paying nearly enough for the delicious and filling food.