We are in the same boat. College and jobs really got in the way of XMAS this year. But in the middle of a People's Republic of Seattle winter, we really need a few days of sun. We're doing the 12th to the 17th (arrive after the marathon, leave before MLK weekend). It's OK though as the observed 15+ year decline in holiday offerings (decorations, etc) makes us feel we're not missing as much. And we have great memories so that's good enough.
The biggest issue I have noticed, besides the typical winter refurbs, is a SERIOUS lack of hours. Mostly dealing with MK. Epcot is set in stone and AK is a half day park anyway. Reduction in EMH has really affected length of stay and planning efforts for Studios and MK though.
Dining demand seems to be OK. Then again, we called on the first day we could. I was a little surprised that more times weren't available but we did get our seatings. YMMV depending on locations.
Crowds are questionable. Even with the marathon and a holiday weekend, Undercover is saying the whole month (excluding New Years) in the 3-5 range. I dunno about that, especially for a national holiday. I'm hoping it will low attendance with nothing much going on 'cause crowds can make or break a visit.
Just think of it this way. You could still be sitting at home or be at the World in January. Easy choice . . .