I would look at allears.net they have pretty good resources. as for if its worth it, it depends on how you eat at Disney, it wouldn't be worth it for me, because I don't eat a ton. I usually do a snack for lunch and then TS for dinner....I woudl struggle to use all the credits and just break even (at $37 per day), but that is just me.
We have used the plan in the past and were happy with it. What I always do is look at all of the menus from the various restaurants that we would like to dine at. I figure roughly how much we would be paying out of pocket and determine if it will be worth it. It was so convenient when the tip was automatically included. I will have to re think my position after our upcoming trip since some of the convenience is now gone since the tips have to be paid separately.
We used the DDP in both 2006 and 2007 but we will not be using in 2008 due to the changes that were made as it is no longer the deal it used to be for our situation. We will just stick with the DDE card.
We've used the DDP since it started. It makes sense for us because we do a TS everyday (that's part of our vacation). So we figured out this year, we will still come out a bit ahead even with the tips not included. We also like the conveinence factor that we don't have to worry about paying when we get there. If you don't want to do a TS everyday, or don't want to have part of your trip tied up with the length of time at a TS, then you probably wouldn't like the DDP.
The tip is no longer covered by the DDP. It is an automatic 18% for party sizes of 6 or larger but it is still not covered by the plan so you either need to pay it in cash or charge it back to your room.