We went 12/25-1/1 in 2017/8. We have been to Disney World many times, but never at Christmas. We usually go Easter week. I see from your signature you have been many times as well.
Since you have been many times, I would encourage you to go at Christmas. The feeling is really magical. But, I would never want this to be someone’s first trip. It is absolutely packed, not even comparable to Easter IMO.
For perspective, on 12/31, we got on a bus to Epcot and it took us 1 hour and 48 minutes to get there. While on the bus MDE notified us the MK was closed to new guests. It was 11:00 in the morning!