I find the TiW to be a more flexible version of the
DDP. Disney advertises you get 20% of with the DDP. Not sure if true, haven't done the math on paying for what you get with DDP.
What I know is, we don't eat like the DDP sets you up. We bring water into the park with us, we don't order desserts (especially with counter service), and it's just not a real savings since it forces us to eat differently.
We've doen TiW twice and loved it. You know what you have to spend to break even ($501), and you get the 20% on what you actually eat. So for us, the added perk of including alcohol is a bonus.
Now, the forced 18% tip doesn't help if you do a lot of buffets as I never tip 18% on a buffet. But, my normal tip is 20% on total (including tax), so it works out for us.
But, we only do it if we're traveling with a group bigger than the 3 of us and/or if we'll be there multiple times over the year. Since we usually do breakfast in the room and CS for either lunch or dinner, we have to make our money back on 1 TS a day. That means typically 10+ days.
We follow the same strategy for TiW as we do an annual pass. If we won't be there long enouth to warrant an annual pass, we likely won't get our money back on the TiW.
Keep in mind, another perk is free valey as long as you have your dining receipt. That can help tremendously if you're needing to park at the resort to eat.
We did Yachtsman Steakhouse this last trip with TiW - we realized it right away.