Excellent.
I had previously heard a fair bit of hype down the years regarding 'Atlantis: The Lost Empire' and now, finally, I can understand why. It is very good. My favourite part of it is the animation which is exquisite, especially across acts one and two with the great amount of detail. The characters are cool, while the premise is pretty fascinating.
Michael J. Fox is a superb cast as Milo, he is fantastic in the lead role. Honestly, none of the other voices stand out to me but that's not always a bad thing - especially in this film. There are no huge individual performances, away from Fox, but they all bounce off each other nicely.
The plot is very interesting, brought to life brilliantly by James Newton Howard's terrific score. It's not near the top of my Disney animated favourites, just through process of elimination really, but it certainly isn't majorly far off. It's a fun experience, one I'd recommend you see for yourself if you haven't done so already.