I'm considering staying there during the Marathon weekend.
After doing a little research, for reference, the shuttle price is 2 euros per person, per trip. Not too bad, but considering its now an official Disney hotel I don't see why they don't include shuttles in the package cost if you book it through Disneyland Paris. Why the price information is not directly on the Disney or Centreparks website is a mystery to me, surely this is important information?!
Also, I tried to book a 2 night 3 days package through the website, and it only included 1 days worth of park tickets, so beware of that. However, it was cheaper than booking through the centreparks website, and if you book through centreparks you do not get any park tickets as default.