The plot idea is very strong and doesn't follow the usual pathways either here on earth or to the skies. The special effects of over 40 years ago can still be admired. Dreyfuss and Garr work well off each other.
It has the usual photogenic casting for this kind of thing plus one of the contradictions of cinema – an action director in love with the slow motion camera.
I thought Leonardo was more J.Edgar as his character aged but overall did a reasonable job. Not a scintillating watch but people like Hoover could never be boring.