Penny Marshall brings a logic to the premise that is sustained through most of the movie. And where the other movies snickered at the sexual possibilities in the idea, she faces up to them with both candor and taste.
For any other full-grown actors who try their hands at fidgeting, squirming, throwing water balloons and wolfing down food in a huge variety of comically disgusting ways, this really is the performance to beat.
What's great about it is that it shows how wonderfully full of toys the world of adults can be. And though this may fall under the heading of tiny, perhaps even fatuous, revelations, it does send you out of the theater with a lighter step.