For my family, the 20% AP has been worth it.
We usually go during Christmas, but have decided to go during Easter and Halloween this year, as well. Christmas is still up in the air, but I'm sure we'll do it.
TIW is blacked out on 12/24 (I believe) 12/25, 12/31, 1/1 (I believe).... and I think Easter, although the CM allowed us to use the AP at 'Ohana on Easter.
For us, the price outweighs the discount. We priced out the TIW for Christmas and our other trips vs. meal plan vs. AP discount. We don't drink much at Disney. We'll have a drink and usually have our most expensive meals (Signatures) on Christmas Eve, Christmas and NYE, when the TIW is blacked out, so it doesn't wind up making sense.
To answer your question, though, the TiW seems to be accepted at more places and offers 20% discount. The 20% AP, as others have mentioned, will be over soon.