Pros
It's great being outdoors in phoenix during the winter, because it doesn't get too hot or too cold. Your getting paid to work-out. It pays better than minimum wage, so it's a good way to get some extra holiday money, and get some job experience. If you get lucky and are placed in the richer parts of town, the views, houses and Christmas decorations are beautiful. Plus everyone is so happy to see you...er...well happy to see their packages. But it's nice not having to deal with angry customers all day.
Cons
If you don't get a regular driver, you have no idea when or where you'll be working on any particular day. They are so busy during the holidays, that there will likely be complications with your paycheck. If you don't have your driver write down a copy of your hours for you, you will have a bad time. Jumping in and out of the truck all day is killer on your knees, even if you are in fairly decent shape.