American Tail's plot is beyond meandering and all the songs are sung badly.
The Great Mouse Detective is better in all but animation.
Friend and I never saw them. And we were bored.
I've noticed that season two of cartoons seem to be where a lot of them fall apart. (For me at least.) One example: Generator Rex is a surprisingly dark and engaging first ten episodes or so. (And then you get to Season 2, where most of the episodes run on f**king moon logic.) But I won't bore you with the details.
And I went back to watching a few of the new seasonal anime. In spite of myself. (I want to like Digimon: Ghost Game more than I do. But the writer can't write...)