Jerry is barely baby faced enough to pull this role off, but the beautiful black & white cinematography by Haskell Boggs helps. It is sappy, but a movie with sappy heart is better than a sloppy heart. Some great characters also. The mad professor upstairs Sidney assists may have contributed to a famous nutty professor role Lewis would portray in 1963.
The first film Jerry Lewis made as a producer, bears in certain sequences his unmistakeably delirious stamp, but the squaring of his genius, at its best in the picaresque non-consequential modularity of the later films, into the round of a conventional narrative structure (a feat he would achieve later, for instance in Nutty Professor) here hurts rather than helps