Gus is hilarious. My two boys (12 and 9) who have grown up with special effects-laden movies and high-tech everything were laughing out loud. It features Lou Asner, Don Knotts and Tim Conway, who are hilarious together and separately with their physical comedy and facial expressions (or, in Tim's case...his deadpan expression is what's hysterical).
Side note: another recommended classic kid movie is The Apple Dumpling Game, also starring those two. But I digress.
The plot of Gus is ridiculous of course, as are the effects. But that's part of it's charm. There's a lot of funny gags all the way through and of course, a warm and fuzzy Disney-esque ending. It also features actual NFL greats that your kids will likely never have heard of, but will be fun for you to see again - Johnny Unitas, a young Dick Butkus, and more. They're obviously having a great time in the movie which makes it extra fun to watch.
They don't make kid movies quite like this anymore and that's a shame. Highly recommended for a throwback family movie night.