My 3-year old loves this game
There are only a few parts she can play on her own - most of the time she likes to sit in my lap and direct the action. Over and over again. She has other computer games, but the immersive 3D world is what grabs her, along with cute animal characters.
Honestly, I'm rather mixed at her addiction. A fatherhood-diverted gamer myself, I'm thrilled to see the budding of my future gaming partner, but I have to actively distract her to a better variety of activities. Zoo Tycoon has a first-person mode which she likes, but it doesn't hold her interest like Brother Bear.
For myself, I'd rate this game below 3, but as seen through my daughter's eyes it's a winner... I'd recommend it to other fathers. However, a kid's game should be somewhat better designed for re-re-re-playability. I wish you could jump to desired levels, change the difficulty, turn off the help functions, and perhaps randomize the placement of some items.