Honestly, it depends on the person/family using it. It's good for some and not good for others.
As I look through the responses given thus far, I noticed something curious. It seems as though a lot of the people in favor of the DDP have been more recent visitors to WDW. I am basing this observation on the signatures listing trip dates.
However, as someone who visited more than 10 years ago when the DDP really was a deal, I find it hard to justify the cost now. As recently as 2004, the DDP included your appetizer, entrée, dessert, non-alcoholic beverages, and gratuity and only cost $35-$40 per adult per day. Yes, I did say it included the gratuity! It was so convenient that you didn't even have to think about leaving a tip. And there was no charge for a missed ADR.
Then they began taking things away, while at the same time increasing the price. For example, gratuity was no longer included (accept for dinner shows), then appetizers were no longer included, then some restaurant locations began opting out of the program or limiting entrée choices available to those on the DDP. Then, after all that, Disney decided to charge more for the DDP during certain times of the year (holidays, summer, etc.). Now it can cost more than $60 per adult per day, plus you have to pay gratuity, and that can add up (especially if your whole party orders the most expensive entrée on the menu).
Nowadays you really need to take into account the way you like to eat. Are you a dessert person? Do you sometimes prefer to eat an appetizer instead of an entrée? Do you drink alcoholic beverages?
I know some people have mentioned that they like to have dessert on vacation, even if they don't usually have it at home, or they would be reluctant to get the most expensive entrée due to price if they were paying OOP. I completely understand that thought process, and I have been there.
But I dare to say for every person who says that, there is someone else who says they don't like feeling like they have to order the most expensive entrée to feel as though they got their monies worth, when they really would have preferred something else, but didn't get it because they thought about how much they already paid OOP for the DDP.
I really think it might be helpful for you to take a look at the menus for the restaurants you plan to eat at and honestly consider what you would order, add up the cost, and see what works best for you. But when making the comparison, don't forget to add the cost of gratuity to both the DDP and OOP options.
And if you have children, don't forget to consider what they like to eat. Are they the type of kids that would be happy eating chicken tenders, burgers, and mac and cheese for every table service meal? If so, great. But if your child enjoys eating the same type of food you do, the DDP may not be for you (unless you are going to all buffet meals). Just some food for thought.
If you still aren't sure, ask yourself this question: Is the DDP flexible enough for my family to be considered convenient?
If you believe the DDP is not for you, and you are either a FL resident, Annual Passholder, or DVC Member, I would highly recommend TIW. The cost is about $125 for FL residents and $100 for AP/DVC. It can be used to cover up to 8-10 people in your party, but the card holder must pay the bill. It is 20% discount on entire bill (including alcoholic beverages). It can be used at most TS restaurants, but the only QS locations it can be used at are usually the resort food courts. It cannot be used at QS locations in the parks. TIW card holders also get complimentary valet parking at resorts when dining at resort restaurant and free parking at theme park when dining at park restaurant.
Hope this info helps! Have a great vacation!!!