Utterly stunning.
There isn't anything to dislike about 'Finding Nemo', it sets the tone perfectly and expertly tells the tale of Nemo, Marlin and Dory. Considering how the story goes, the film does an outstanding job at seamlessly switching between Nemo's adventure and his father's - it's truly terrifically done.
This also includes a whole bunch of memorable characters and voices. Alexander Gould, Albert Brooks and Ellen DeGeneres are the obvious stars as the early mentioned trio. There's a load of others though, with Willem Dafoe (Gill), Geoffrey Rush (Nigel) and Barry Humphries (Bruce) all giving excellent performances.
The animation is superb, a few moments haven't aged as greatly but the absolute vast majority still looks unbelievable. The premise is funny, cute and heartwarming - as it keeps one's attention from start-to-finish. The score is fantastic, too.
Highly recommended.