Often I laugh, but just as often it makes me nervous. That Jerry is infantile also means that he's excessive. Anything goes, without regard for norms of intelligence or taste. Even when Lewis has a good comic idea, you get the feeling he doesn't know when to stop. He pushes everything just a little too far.
Most comedians create a sort of magical world, in which their particular brand of insanity rules.
Such is the case for film comedy on nearly every level, all the way from the Three Stooges to Woody Allen. Lewis is nearly alone as an exception to this rule. His persona is never able to rearrange the world to his own liking. As a result, you don't get a sense of freedom from his films, the way you do, for instance, with the Marx Brothers or Monty Python. You never escape from that voice in the back of your mind that keeps on telling you how stupid this all is.