As a player you can get contract offers, which is a nice addition over Madden 12. Other than that it is honestly pretty similar, just with a bit better graphics and gameplay (for the most part, there are many issues though). If you're only doing Superstar mode you would probably like the Twitter/News Feed also since your player can sometimes get mentioned on there to give you a little more immersion.
Overall, the new Madden has its faults, but I'd still say its worth the money. Maybe try buying a used copy and just keeping Madden 12. Then you can try out the new one and return it if you're not a fan, and still have your Madden 12 to go back to.