It's an animated movie, which is done very well. I was laughing hard throught the first half. After seeing the trailers, I didn't think that it's my kind of a movie. Trailers are misleading. There's a lot of music and singing, and some do it really well. I didn't think that Brittany Murphy was excellent, but she was decent. She had one difficult song, Queen's Somebody To Love, and did it fairly well. Nicole Kidman sings too, not bad.
Latino penguins were very funny. It was such a contrast to get into their colony after the "scottish" penguins colony led by Hugo Weaving. Well, maybe it wasn't scottish, but some kind of "british" accent. Entire change of athmosphere when you get into latino colony is hilarious. I think this is the first time I see in animation how latino culture is shown in a non-patronizing and very poistive fashion.
The second part has a very strong shamelessly plugged-in environmental message. I thought it was a little over the board, but it's Ok, it doesn't spoil the movie too much. The episode in the Zoo reminded me of One Flew Over the Cuckoo's Nest. Overall, it's a very enjoyable movie, I'll get the DVD once it's available.
Update: I looked at the soundtrack of the movie, and it doesn't have "The Leader of the pack" song! I thought this song was so appropriate in the context of the movie and performed beatifully. How come they didn't include it into the soundtrack?! Also, Robin Williams' rendition of "My Way" was hilarious. I heard the spanish version by Gipsy Kings first, and liked it. They also cover "Hotel California", and do it darn well.