I think winter weddings are wonderful. :) Summer is awesome for outdoor weddings and I think are more convenient and easy to plan, but winter weddings are so beautiful too! If you and your fiance prefer the winter season, why not get married in it?
For me, a Christmas wedding is a little iffy. If you are planning an intimate family affair it could work out, but asking guests to give up one of their only holidays of the year with family seems selfish. If it were extremely important to a couple to get married on Christmas, I'd hope they'd be a little open minded about a large group of guests not being able to attend.