Particular applications of the distinction between Law and Gospel sometimes cause controversy and give rise to criticism.
At the level of the basic distinction itself, however, I should think that most of that controversy would dissipate.
Shortly after the definition of “the Gospel” quoted here previously, Niels Hemmingsen gives such a basic, concise summary of the distinction between Law and Gospel:
“From these things the difference between Law and Gospel can be easily understood. For the Law promises life to those who do the Law. The Gospel freely [gratis] offers salvation to those who believe in Christ. For the gift of God is eternal life through Jesus Christ our Lord, according to Rom. 6.”