I very much enjoyed this film, but understood going in that I was going to be immersed in silly physical gags, imponderably head- scratching plot twists, and rear-projection "outdoor" scenes. And I got all of them, in barrels. Even without McHale (Borgnine was filming "Flight of the Phoenix") it is a worthwhile creative endeavor.
Tim Conway plays Navy Ensign Parker who must disguise himself to escape from a sticky situation -- unfortunately (one would think) for him, the uniform with which he absconded belongs to the son of a 4-star general. Mistaken for the misplaced general's son, Parker constantly finds himself in situations for which his incompetence ill-prepares him, and yet he not only succeeds (incredibly, but consistent with the show's expectations) but does so while battling the nervous stresses added by the continual presence of Capt. Binghamton.
If you are a fan of the show (or of comedies of this silly sort), then you will enjoy this, which is actually an elevation from the average episode of the later couple years of the series.
If you desire "Philadelphia Story" sophistication, or "Bringing up Baby" is the peak of your tolerance for sight gags, then this is not your cup of tea.
It was definitely my cup of tea.