We were there 12/25-29 and had varying experiences, but SO glad we had plenty of ADRs. On Christmas day around 1:30 the CS at POFQ was a breeze. On the 26th at around 2:00 we wanted lunch (later than usual!), we were turned away from 2 CS restaurants in the Magic Kingdom and ended up grabbing ice cream to tide us over to our 5:00 ADR at Tony's. At Epcot on the 27th we had ADRs for lunch and dinner so we didn't have to wait in them but the lines in World Showcase looked really long later in the afternoon. The 28th we ate at Earl of Sandwich in DTD and the line wasn't too long but the place was a zoo and we had to stand around with our food for about 10 minutes before a table opened up. We had a late dinner ADR at Spoodles that night. Then on the 29th we had an ADR at Sci-Fi at MGM and left by 2:00, but it was just starting to get busy as we left.
So... I would make plenty of ADRs, but if you want to go CS for lunch go EARLY. I couldn't tell you for dinner since we never tried to do that. Breakfast at POFQ wasn't too long of a wait either.