In this umpteenth remake of the George M. Cohan-Earl Derr Biggers play Seven Keys to Baldpate, Desi Arnaz Jr. plays Kenneth Magee, the young writer who bets that he can bat out a mystery play in one evening. Magee squirrels himself away in a forbidding old mansion where, unbeknownst to him, a bizarre family reunion is scheduled to commence. As the participants begin dropping like flies, Magee finds himself in the middle of a genuine mystery. At least, he thinks he does. At least, the audience thinks he thinks he does. Of historical importance is the fact that House of Long Shadows represents the only co-starring effort of those titans of terror Vincent Price, Peter Cushing, Christopher Lee and John Carradine. The highlight is the cozy tete-a-tete between Price and Cushing during the climactic party scene.
~ Hal Erickson, All Movie Guide