As a ballpark estimate, at least 120 of the 860 pages change every year. Some of those are reader comments, of course, and the usual updating of prices and facts.
The '09 edition has a whole new set of survey research on the Disney resorts. The restaurant reviews are updated. The touring plans for the Studios will be different with Toy Story Mania. There's a new (and updated from '08) spa chapter. New research on which car rental places save the most money (even if you're using discount codes). And the usual smart-alec comments.
That being said, we know Disney's going to change the meal plan, resort and ticket prices on Sunday. Those won't be in the first 2009 printing, but we've already started posting those book updates on the website. If your trip is after February 2009, you could wait for the second printing, which will have everything, too.
Len
PS: And you get free access to the online crowd calendar, which predicts wait times and best parks to visit every day for the next year. If you haven't looked at that, do so - it's pretty cool. We also go back and check how accurate the predictions are versus actual wait times, and those results are posted (free) on the website too. So far this summer, actual wait times are +/- 7 minutes from our predictions, on average.
