• They go up much faster than than their "real" counterparts.  Most come pre-lit.   No sawing off the trunk and wrestling with the tree stand.
• They are safer due to the fire danger that real trees can pose if they dry out.
• They are kinder to the environment as some are made from recycled materials and they are re-used year after year.
• You can put an artificial tree up as early as you please.  So if your Christmas Party is the first weekend in December you can have your tree up and it will still be just as beautiful on Christmas Day.

The biggest negative of an artificial tree is the lack of that wonderful smell that you can only get from a real evergreen. 

Here's a Tip:  If you use an artificial tree put some evergreen potpourri at it's base.  Then you can have the best of both worlds.