Since its earliest productions, Shadowlands has split critics. While many believe the play is a powerful study of the human condition that left audiences openly weeping, some have questioned the authenticity of this portrayal of C. S. Lewis and Joy Gresham. Several critics highlighted inaccuracies, such as the fact that Joy really had two sons, not one, and that both Lewis and Joy were much more difficult people than Nicholson's portrayal suggests. Many compared the stage play to the original BBC television movie, somewhat unfavorably.

Of an initial British production in the Queen's Theatre on London's West End, John James of the Times Educational Supplement wrote, "William Nicholson's witty, humane script brings them both to theatrical life so truthfully that we are caught up in their autumnal romance." The unnamed critic of Financial Times argued, "The play describes but does not illustrate. We never know why...