FFS can bite both ways. It doesn't tell you if it is a bass or not. You can catch white bass, Crappie, Catfish and Drum using FFS. Don't ask me how I know. You can also get screen fixated and lose a ton of precious tournament time just looking for or casting to fish that aren't Bass. Again don't ask me how I know. It can also get really interesting when you cast to a fish and it swims away, sometimes rapidly. It's a tool, it helps you see what is going on under the water and the interpretation of what you see is what determines how useful it can be for you.
I have been using FFS for about three years now. I don't get to fish nearly as often as I'd like to. I don't use FFS all of the time, maybe half to a quarter of the time at best. But I do use it when I want to know more about whats under and around me. Yes, it is a rush when all of the stars align and you get it all right. The cast, the retrieve and to see the reaction and the "eat" of a good fish!
My two cents,
FM