Firefly is classy-casual, and tasty
Firefly reminds me of the Blue Jay Cafe (also in San Francisco, on Divisadero) but more expensive and a little nicer-looking. Both serve home-style food, with Firefly being a bit more refined but also a bit more expensive.
Firefly feels comfortable, as if they remodeled an old house and made it into a nice eating space. Every dish was great, especially the appetizer of goat cheese encrusted in pistachios and served with a little salad of greens and strawberries in a light vinaigrette; wow.
Staff was low-key and friendly; the ambience looks like a nice-but-casual space.
I would go again and again, but not every day if only because of the cost (for my budget, it's not every day food prices).