Its a cool game where Isaac can change characters (little plastic statues) on the portal and they instantly appear on the screen. You need some specific characters to unlock certain mysteries in the game. There are a total of 32 characters so far, three comes with the game.
I read that so far this is the best selling figures collection of the year. Activision has sold more Skylanders then Hasbro has sold Star Wars action figures, which was the winner of every past years.