I went Monday to the La Brea location before the Kings-Avs game. I got the signature Umami burger and the tempura battered onion rings. The burger was a bit small for the price (6oz/$10) but it was actually very good. I don't recall all the ingredients but there was sauteed onions, mushrooms, a little crispy disc of parmesan cheese, & their homemade ketchup. But all the flavors blended together almost perfectly. And the onion rings were just as good if not better. Except the condiment they serve with it, which for me was the ketchup, came in a little soup spoon. I'd love to say that I'll go back there again & try the other burgers. But the service sucked so badly that I probably never will, at least not to that location.
I tend to go in the early afternoon when it's not too busy and I've never received bad service. I do hear that service there is a mixed bag. That's too bad. Try the Los Feliz location next time. They serve beer. :)