We will be in Disney the same days! We go almost every year at this time and the main thing you need to realize is it will be extremely busy! Parks close to capacity and it will be wall to wall people! You must have a plan, have your dining reservations booked early, you FP+ selections as soon as possible and plan on being at the parks at opening to take advantage of low crowds, or plan on staying super late.
That being said it is also the most magical time to go, lots of holiday decorations, parades, special fireworks, shows etc. New Years Eve is probably the busiest day of the year, there will be special fireworks/shows in all the parks except AK. Plan to be at the park of your choice prior to opening and plan on staying all day, if you leave you will probably not be let back in. We never stay up for the NYE fireworks, so our typical NYE involves being at AK at rope drop, its so dead that we manage to everything we want with no waiting and are ready to leave by 1pm. That evening we have dinner at DTD and then head over to the Poly to see the 8pm firework show, it helps to miss all the madness.