Wanted to chime in...I went last year (seems like forever, but only a few weeks ago!) and stayed Dec. 1-7 at Disney. It was our first Christmas trip and first trip to stay onsite. I literally cried when I seen the Castle in lights!!! My 7 year old son gave me a big old hug and said, "it's OK Mom, it's not broken, they just decorated for Christmas!!!" So, In my opinion, it is a WONDERFUL time to go.
BUT please beware......what is described as LOW crowds, are LOW crowds for DISNEY. Not that there will be small crowds, just that there are usually tens of thousands, there will only be ten thousand....and even this is putting it lightly.
For a first trip, in my opinion, there are two things that are difficult to wrap your brain around before experiencing for yourself....1) the enormity of "Disney World"-meaning all 4 parks, DTD, Disney Hotels, and Water parks. 2) What a crowded really is!!!!
Whenever you decide to go....it is a Magical Place, and you will have wonderful time!