We have it and it totally depends on your dining habits & if you drink alcohol at most meals. We got it once a few years ago when DS was still younger & eating kids meals & as a family of only 3 it took us awhile to reap the rewards. We also didn't plan enough meals at places that accepted it. I think there are more options that take it NOW than there used to be. At that time I think the price for AP holders was $65. It took us 2 trips to get our money's worth back from the purchase but we eventually DID. We ate at a couple of places that didn't take it & didn't realize it before etc.
THIS time though it's been great. DS is now 15 and eats more than both of us sometimes. We got it on our spring break trip & used it at La Hacienda, Chefs de France, Via Napoli, Ohana, Prime Time Cafe, Pizzafari and The Plaza. Anyway, the specialty margaritas at La Hacienda were $13 so 20% off is 20%.

We saved like $120 I think it was on that trip so we more than recovered the $75 AP holder price. We have another trip next week and will use it at Crystal Palace, Biergarten, Boma, in the AK park (probably at Pizzafari or Flame Tree BBQ), maybe at Prime Time Cafe again and Kouzzina's on the Boardwalk. We also booked a meal at Teppan Edo which does NOT take it but we can get 10% off with our AP's. Those buffet places are crazy expensive (CP is $43.66 p/adult so we will save over $26 at that meal alone) so heck yeah it's worth it for us.
I think the larger your party the more benefit there is. A family of 5 or 6 would really make out with it since it covers a table of up to 10 people. Since it is a percentage based discount the more you tend to spend on your meals the more you'll save. Just be sure to make your ressies at places that take it. Places like Yak & Yeti, Rainforest Cafe, Wolfgang Puck etc. do not accept it.