This movie tries hard but never quite makes it to 'great'!
First, the story is a bit too predictable. Three unlikely companions - Manfred the woolly mammoth, Diego the saber-tooth tiger and Sid the sloth take it upon themselves to unite a lost baby with his 'herd'. The rescue-and-restore operation sees them go from bickering, can't-get-along reluctant companions to loyal, willing-to-die-for-each-other friends.
The highlight of this film is, undoubtedly, the wonderful squirrel, Scrat. The highly inventive, usually disastrous, unceasingly persistent and endlessly fruitless travails of the squirrel transform this movie from a decent movie to a pretty good one. The dialogue is extremely funny in parts, especially Manfred's one-liners delivered in the classic deadpan Ray Romano voice.
My biggest problem with the film was that I found the voices of the main characters very unconvincing. Having watched Ray Romano in 'Everybody Loves Raymond', its very difficult to reconcile Manfred the woolly mammoth with his voice. Also, Diego the saber-tooth tiger's voice is a bit too cultured to quite match the character. Only Sid the sloth's voice is convincing enough.
A good movie overall, elevated a few notches by the delightful squirrel.