This is a horror film aficianado's dream - the only time that Peter Cushing, John Carradine, Christopher Lee and Vincent Price appeared in the same film and the same scenes together!
Forget about the ponderous build-up to the appearance of the stars and the lamentable arrogance of Desi Arnaz Jr. in a forgettable role (he can't hold a torch to the acting abilities of his famous co-stars!). The cliched surroundings of a dark, haunted house can also be criticised; but this is the ideal platform for the horror greats on show to perform in a typically professional fashion.
Peter Cushing's drunken characterization is very well done and Vincent Price's grand dialogue is reeled off in an extremely believable way. Christopher Lee's role is also enjoyably wooden and in the mould that we have come to expect over the years!
The film is guilty of faulty pacing - the start is slow but the execution of murders later in the film comes relentlessly and with little subtlety in thought or execution. However, the sole purpose of the film is to provide a horrific who-dunnit in an old-fashioned way with the top stars of the genre!
The ending also ensures that the viewer is never quite confident that the story's resolution has been provided.
Not a masterpiece by any means , but a fitting tribute to the stars in the horror field, who have entertained us so much in the past and will continue to do so in the future!