I'd never heard of the Flame Broiler, until it came to the Tempe area. According to the shop's website, the founder is Korean and when he was working right out of college, he couldn't find a healthy place to eat so he started this place and it has grown and spread ever since.
So, firstly, the taste of the food is decent. It's not incredibly yummy, but it's also not terrible either. I had the mini bowl of chicken and vegetables and my friend got the beef and chicken with brown rice.
While the whole concept of Flame Broiler is that it serves healthy food, I would say that it's not really healthy since the meats are doused in salty sauce. There are several different kinds of sauces that you can put on your meal. The Magic Sauce is like a soy sauce/teriyaki sauce blend. The hot sauces are kind of strange tasting, mostly because they're too tangy/vinegary.