I had the first two taped off TV when I was a little kid, and I loved them. Then Stuart Little 3 came out, and it was the most underwhelming movie I'd seen at the time. It doesn't have any of the charm of the first two movies. In fact, despite being the only installment with a G rating (whereas the first two installments received PG ratings because the villains say "damn" a few times), it has far more crude humor than either of the previous ones did, which I found very ironic. The crude humor is also offsetting from the very very clean non-offensive nature of the first two films.
Also, having re-watched the trailer after not setting eyes on this movie since my Junior High years (because I don't usually acknowledge that this movie exists), the animation is absolutely atrocious.