Is there a blander comic actor than Tim Allen? Though he spent eight seasons defining his persona on Home Improvement and has worked steadily (if generally with a lower and lower profile) in movies since then, Allen has never exhibited much in the way of charisma or a distinctive identity. He's that guy you say hello to every day in the office and yet can't remember his name even after several years. I suppose that makes him perfect to play the American everydad in The Santa Clause, but it also means that the movie has a big personality vacuum at its center, and since Allen is in pretty much every scene, that ends up being quite a drag.
Allen's Scott Calvin is your typical movie divorced dad, more focused on his job than on his young son, although at least he's portrayed with more sympathy than a lot of cinematic fathers. He does his best to provide a nice Christmas for his son, and his ex-wife is the one who commits the terrible movie sin of hinting to her son that there might not be a Santa Claus. Scott, too, is a little shaky on the existence of Santa until he encounters the real thing on top of his roof on Christmas Eve and accidentally startles Santa into falling off the roof to his death.
A family film based on the death of Santa Claus? Yep, but it's glossed over as nonthreateningly as possible (Santa literally disappears into thin air), and the movie's real focus is on Scott's inadvertent recruitment as the new Santa. The potential for awkward comedy in his transformation into a bearded, fat, white-haired man is pretty much squandered, and the movie is full of discarded plot elements, including Scott's job and something like a year of time between two Christmases, which passes unnoticed in one or two scenes. Beyond the dodgy pacing, the movie runs through some stock lessons about keeping a childhood sense of wonder (Judge Reinhold as Scott's ex's new husband is the movie's avatar of humbug, in yet another case of psychiatry versus Christmas faith).
Like Santa Claus: The Movie, The Santa Clause comes up with an involved Santa mythology, and part of it involves the fact that elves look like children despite being thousands of years old. This means casting child actors instead of little people, and leads to one extremely icky moment in which a girl elf flirts with Scott. Tim Allen flirting with 10-year-old girl? Not something that should ever be in a movie. Mostly, though, the mythology is half-assed in service of things like reindeer fart jokes and sappy lessons. Supposedly, the role of Scott Calvin was originally written for Bill Murray, and even a sloppy, forgettable script like this might have worked with Murray as the lead. With Allen, though, it's just flavorless Christmas mush.
The True Meaning of Christmas: Don't stop believing.