It is not hard to see why this film was so popular when it was released theatrically, and easy to understand why it failed to create a new generation of fans. Apparently, it is not a film worthy of being a classic, since there is nothing special about this film. In fact, it is inferior to a similarly-themed family classic released in the same year, "Harvey", starring James Stewart. In both films, the central character is accused of being mentally unsound for communicating with animals.
Still, this is a well-made movie with reasonably good writing and direction, featuring talented casts which elevated the film. In particular, Donald O'Connor displayed as much acting range here as James Stewart did in "Harvey". Both of them have this rare ability to emit boyish innocence, something which is even rarer nowadays. Best known for his comedic second-banana performance and exuberant dancing in "Singin' in the Rain", he has the opportunity to display his dramatic acting ability that is sadly overlooked.
This film is definitely a good option if you want to have an enjoyable time with the young children.