The Nintendo DS version of the game was created by developer Other Ocean, is rated E10 + (Everyone 10 and older — content that may be suitable for ages 10 and older) by the ESRB, and follows the exact same storyline in an entirely different platforming adventure. (tmrzoo.com)
As for the fun factor, I've put 32 + hours into this game and I've had fun the entire adventure... I always get the sense when somebody complains about it not being fun what they really mean is it doesn't hold my hand and give me the exactly same storyline everybody else will experience ala Assassins Creed, Far Cry, GTA, Fallout, etc... (n4g.com)