I think it's good.
To me, 'The Santa Clause 2' runs the original film very close. I found the plot to this one more consistently enjoyable, whereas the first one starts off stronger than it finishes - I'd still class the 1994 production better, but this is a solid sequel in my opinion.
Tim Allen reprises his role as Scott and continues to be showpiece of the film. Elizabeth Mitchell is decent as Carol, while Spencer Breslin - who is good in 'The Cat in the Hat', and yes I like that film - fits his character well. My point being, this has a slightly improved support cast.
Going back to the premise itself, it's nothing to take seriously of course but I felt suitably entertained by it. Intrigued to see where the second sequel goes.