I've had several AP's. For me, part of what prompted me to get one, was the savings off our hotel room. Disney's deals vary. Sometimes the best deal )on a week long trip) is the AP discount (plus Tables in wonderland), often the best deal is the general public discount. (enough to cover the added cost) If I think I'll be able to go more than once in a given year, it is often worth getting an AP.
The other discounts don't usually do much for me. First, you have to ask for it. Forget to ask? Too bad. Second, the Tables in wonderland discount usually eclipses any dining discounts. The merchandise discount is only like 10%, only at certain places, and is the same as other discounts. (Like
AAA or Disney Visa.)
One new tiny advantage of an AP is how the new FP+ works -if you will use your passes for more than one trip to WDW. In order to book FP's, you need to have a ticket registered in the system. Any ticket will work, but having one AP under each person's name is just easy.
Rarely AP holders get invited to previews of new attractions/shows. It's rare, but if the magic happens, it is pretty neat.
As others have said, current AP discounts are often not much better than general public ones. Also, when offered, they often come out very late.
Figuring out price differences is also a tad complicated sometimes. You have to do all the math for your individual situation to find which is the best deal.