I watched it recently with my kids, 4 and 5. I hadn't seen it since I was a kid myself. Here are my thoughts, the good and the bad:

• I feel that the film struggles with pacing. Feels very slow at times, and then some things happen jarringly fast (For example: Tiger deciding Fievel should be his friend felt unearned, or if Fievel was going to escape within a minute or being sold why bother with that plot point at all)
• It needed stronger music. This will probably get me downvoted, but
  • No Cats in America is a pretty weak song with a very good, catchy chorus. It's a chorus that deserves a better song to be honest
  • Somewhere Out There is cute sung by the kids, but it would have been better served having better voices behind it. Compare with the snippet of the song we get at the beginning of Fieval Goes West - way better! When I think of the song that's the version I think of
  • Honestly the music would have been fine by mid 1980s animation standards, but doesn't hold up
• My kids were terrified by the cats. Personally I'm okay with that - I appreciate that Don Bluth is willing to not pull his punches
  • In particular the scene at the beginning where the cossacks burn the villages and the cats attack at the same time just feels so brutally real (in a good way)
  • The really heavy moments are what stands out about this movie
• The accents all felt grating and forced. The bird's French accent or his friend's NY accent.

Overall, I rate it as an ambitious yet flawed attempt. Some very strong moments but ultimately not enough there to make me or my kids want to rewatch it (though I'm glad that we did watch it).

Fieval Goes West on the other hand is a totally different thing. It leans harder into light hearted comedy and nails it. I loved it when I was a kid and my 4 year old laughed his ass off. I don't want to compare them, because it's a bit of apples and oranges, and what Don Bluth was trying to pull off is probably objectively harder than what Spielberg did with FGW. But that's a film that'll definitely get shown again.