As a DVC member you can buy TIW for $150. This enables a 20% discount and free valet parking. The discount applies to both food and drinks (beer, wine, cocktails).
So, normally, you would need to spend $750 over a year to break even. ($150/.2)
However, currently AP and DVC discounts are yielding up to 20% on food only, so it is much harder to break even.
Take a look at this chart detailing the various discounts. http://allears.net/pl/disc_dining.pdf
If the restaurants you like have 20% discounts through AP or DVC, then the only way to break even is through $750 of drinks. If the restaurants you like have a 10% discount through DVC or AP, then you need some combination of $1500 in food or $750 in drinks to break even.
For most people, I would not recommend the TIW this year.
Agreed. I would add that I think Disney is realizing that TiW is too good of a deal, and they're using this one year of DVC and AP discounts at restaurants to get people out of the habit of using TiW so that when they take it away, and subsequently take the AP/DVC discounts away, people won't complain as much. You heard it here first.
Keep in mind that the 20% AP discount is set to end on September 30th. So, if you were planning your trip after that date, it might still be worth looking at.
We debated this too with the same parameters (DVC, AP, & Chase) and bought the TIW on our trip in May. We are heading back for F&W in October and figured another trip next year to make it worthwhile. But, we like to eat at bars with drinks!