I live in San Francisco, and San Francisco has good food...but nothing like Firefly! The food is delicious, service is friendly, and the atmosphere is super fun! Only downside is that it's a little dimly lit and can get a little loud. I went on a Saturday night, so if you're looking to have a good conversation with your dinner-mates, go at a less crowded time or just try another place.
They also have DELICIOUS sangrias - delicious enough to inspire me to make my own the next night. Sadly, mine were not as good.
Overall, if you're in vegas and want to get away from the strip, come here!