I love the Season of Advent because of the Scripture readings and themes and hymns heard in Divine Service. Those elements heard on Sundays and during midweek Services provide the theme for each day leading up to Christmas. As a preacher I love the texts for Advent and the hymns that accompany them.
I think it is important to observe Advent and not Christmas until it is Christmas. I think it is healthy so that Christians would celebrate Christmas during the twelve Days of Christmas and focus on that period of time rather than the period of time October - December 25. Though, I am not quite as concerned about it as I once was. During Divine Service I observe it rather strictly but outside of the Divine Service I am not too worried.
The Season of Advent has a penitential aspect. Quite different than the festive atmosphere that often accompanies much of December with office parties, school parties, etc. the Church observes a period of repentance and reflection. Preparing for our Lord's return is a theme that runs throughout all of Advent. How does one prepare for His return? Our Lord prepares us through bringing us to repentance. What a contrast to much of what happens in December.
Advent is a season of anticipation. It is a longing for our Lord Jesus. Amen. Come, Lord Jesus.