Faerie Fire, as is the way with all spells that require a saving throw, is only really as good as the saving throw needed to avoid them. That being said, Faerie Fire is still one of the best spells in your party's options, even if it is to be on the safe side. It should be noted that although it requires a save, it only requires one save, so when it is successful, the effects are successful for the entire one minute of its duration.