We cruised 12-22-02 through 01-05-03. The weather was good, but a bit nippy in the southern-most ports. Be sure to bring a heavy coat. The only falls we saw were the ones outside of Puerto Montt, in the lake district. We had no extra time before the cruise, that would have been needed to do that.
I highly recommend the "Senior Tango" tango show in Buenos Aires. You can sign up for this tango show on the street beside the cruise terminal. It is by far the most wonderful stage production of any sort I have ever seen. The food is outstanding and the wine and dessert are included for only $50 per person including transportation from the pier and return. The ship tango tours were not nearly as well received. The show gows from 8:00 until 12:30 A.M. They do have a web site that can give you a sample of what it is like.