When you scratch the surface, Disney Infinity is sort of a system of games, and various characters and story modes can be unlocked by buying various figures. You can also unlock items and such by buying little plate things. But it's so much more than that. It also has a sandbox mode. You can create and share maps, and these maps could be about racing, fighting, whatever. It's probably a lot easier to just show you.
Disney Infinity's Youtube channel (http://www.youtube.com/user/disneyinfinity/videos) has a lot more videos of the game, too.
P.S.
Some Disney parks have started a thing where they give you a bracelet that takes care of most everything that you need for your stay there, including your dinner plan, park tickets, etc. When your vacation is over, you get to keep the bracelet. My mom heard that you can use that bracelet to unlock a special game in Disney Infinity.
'Roll' playing... I see what they did there lol
Disney wants some Skylanders action.
I was a little excited when I first heard of Infinity, having that child-like delight when it comes to Disney animation. But as much as I pine to revisit those movies in video game form, I can't justify the damage all the extra content will do to my wallet.
Plus where're The Lion King characters at? :[